Monday, May 16, 2022

NiBx Browning A5 12 Gauge - Resurrecting a Legend - Part 3

NiBx Browning A5 12 Gauge - Resurrecting a Legend - Part 3

We get all excited over the newest shotgun with an extra big bolt release button, phallic symbol length magazine tube, and a charging handle about the size of a baby arm, however in reality, the Browning A5s will still be around 100 years from now long after the others lay broken in a gunsmith’s parts bin. This is the last article of a very long-term nearly five-year three-part series focused on resurrecting a 1926 Browning A5 12-Gauge shotgun. In this part 3, I am cutting the barrel down to a 18.5-inch, reducing magazine capacity to standard 4+1, finishing up the furniture, doing some final tuning and attaching a sling.  Don’t worry, there is more A5 fun to come. I have two more cheap A5s no one wanted which I have converted to Shockwaves with two Sarco virgin Belgium A5 receivers. Yep, my next projects will be making non-NFA “Shockwave Firearms”. If you are an A5 fan read on.

In Part 1 of my Browning A5 12-gauge resurrection, I deep cleaned and updated the 1920s vintage Browning A5 with new recoil and action springs and friction rings, a Browning Speed-Feed lifter parts set was added for faster and smoother reloads and a giant amount of magazine capacity was added in the form of a Nordic Components MXT tube extension to a 9 +1 total capacity. 

In Part 2, the entire gun was disassembled and WMD NiBx (NiBo + Teflon) coated which frankly is about as amazingly awesome as any 28-inch barreled A5 can get. The WMD coating process made every part look new. The problem was the MXT extension nut stripped out after a few hundred rounds and shot the magazine tube across the range like a spear gun. Nordic sent out another under warranty which was used in Part 3.

That was well over four years ago and now we have the final format, a Rhodesian style Browning A5.

The Browning A5 was used in both World Wars as a trench and combat shotgun and they learned a lot about what worked in warfare, which was more capacity and a shorter barrel with open improved cylinder choke. The Rhodesian model was really the pinnacle design of those defensive needs.

The un-officially named A8 was actually produced for the Rhodesian military so named for its 8+1 capacity and shorter 23-inch barrel with improved cylinder choke. There is some conflicting information that FNH and Remington also made some additional international police models with some shorter 20” barrels versions which only held 7+1. The Rhodesian was so named for its extensive use in the Rhodesian South African war 1964-1979. Technically, the shotguns were FNH Belgium made, shipped to South Africa and smuggled into Rhodesia. The actual Rhodesian models were sterile with no labeling, and were just hand “Rack Numbered” with a vibrating steel pen. These were produced by FNH with eight shell magazine tubes and amazingly long forends. 

Allegedly there were less than a 1000 ever made, some say less than 500, since the serial numbers only indicate a three digit numeric rack number. In the 1990s only about 300 were ever imported by Century Arms into the US. The result is they are VERY rare and expensive when they do come up for sale. Finding and buying a Rhodesian Browning is akin to buying Vibranium Armor - since that does not actually exist, you get the idea. The last Rhodesian I was able to find sold for over $5000 about ten years ago. It was the 1960s factory equivalent of a Browning 3Gun A5.

The insane 32-inch overall barrel length (28-inch barrel plus a 6-inch corn cob compensator/variable-choke) was pointless when 90% of the time I was blasting away at 25 yards or less. The insane barrel length was far from a handy length.

After the Part 2 A5 Resurrection build article, I found that the reality of an already heavy all steel Browning A5, obscenely long barrel, and ten total rounds loaded was so heavy it was a body building exercise to shoot. The two times MXT mag tube extension failure was also a motivator to rethink capacity. Most of the time, I was only loading about seven rounds so why have a gun that could hold ten and weigh 10.5-lbs loaded. Another MXT failure had me thinking the stock steel magazine tube cap was the only reliable option. Sadly that meant this Rhodesian style build would only be 4+1 rounds. 

As shown in this Part 3 Rhodesian build with the shortened magazine tube, correctly fitted and shortened solid walnut butttock, and mounted sling, the gun is now down to 8.4-lbs empty and balances perfectly mid-receiver with an overall length of 37.5-inches. I could probably hog out another half pound of walnut from the buttstock, but the balance is really nice at this point.  Break out the hacksaw, we are going to talk though a lighter shorter beast. More on the magazine extension later.

Before the hatemail flows of - “you idiot, you hacked a museum quality A5!” This specimen was originally sold at an estate sale for about $150 to my FFL and to me for $200 - it never was a museum piece. Even if it was, John Browning would be in favor of building something unique with one of his creations. With that noted after the WMD treatment, I actually had someone offer me $3000 as it seems to be the only NiBx coated A5 in existence. With the WMD coating it could in theory be submerged in salt water for 50-years and still come out operational.

What I wanted was a faster, shorter and lighter version like a Browning Rhodesian. What the A5 does need to function is typically a minimum a 1-⅛-ounce load. Lighter loads had not been invented back then so the A5 shotgun was not designed to cycle them well. I can get super light 1oz load stuff to cycle, but it requires removal of friction rings on this build.

I do see a lot of armchair A5 “Expert” forum jockeys note the A5 needs the barrel length and weight to be reliable, yet this 18.5-inch barreled chop job runs great. With the correct load, right spring and friction ring setup, the A5 will run just fine with an 18.5-inch barrel. Most of the time my setup is left in the “heavy” spring/ring configuration.

The capacity was scaled back to 7+1 rounds with the Nordic Components MXT +2 magazine tube extension. Esthetically, the magazine tube length matched perfectly with a 18.5-inch barrel, looked fantastic, but well… shot down range like a harpoon spear again - alas another stripped MXT nut. I love Nordic, but the adapter should have been made from steel to handle the goofy recoil and less than perfect thread on the magazine tube. Back to the proven Midwest Firearms all steel swivel sling magazine tube cap and stuck with 4+1 capacity.

Looking back, I do wish I would have done some beveling and smoothing work on the magazine reloading port area before nibx coating. The abrupt edges around this area do seem a little harsh after getting used to competition tuned shotgun reloading ports. On the next A5 builds, the reloading ports all received a lot of smoothing and beveling.

In theory chopping the barrel is pretty quick, but doing it correctly to deliver a uniform shot pattern involves more than a hacksaw and a file and should include a recrown. According to ATF standards, the barrel length is measured from the closed bolt face to the end of the barrel with any chokes removed. Measure, tape, cut, and file… but, crowning proved an issue. Generally, I use Pacific Tool & Gauge gunsmithing tools and they sell the roughing muzzle cutter and the finishing crown cutter. You technically do not need both, however the roughing cutter is designed to chew down wonky hacksaw cuts and the finish crown cutter is not very tolerant to that initial mess. 

The barrel was cut and leveled as good as my eye could get. What I thought was an amazing hand file job on the crown was, of course, considerably off square after using both Pacific Tool crowning tools. So $150 in on more specialized tools, I had a beautifully square 11-degree crown on a 18.5-inch barrel. I will not this crowning delivered such concentric patterns that I thought heavily about recrowning all my shotgun barrels.

After handling many A5s since purchasing this one, I realized the furniture on this model was actually stunningly good and had some character without being abused. I decided to flip from the polymer stock shown in the other builds back to the original wood version, do a bit of steaming out the dents and trimming the original wood buttstock and buttstock replaced with a limbsaver pad and the stock drilled for a swivel stud. 

After citrus stripping, the checkering was cleaned with rubbing alcohol and a toothbrush was all that was needed to prep the furniture for a re-lacquer. Some people go nuts with sanding hand checkered vintage furniture and they usually end up losing a lot of detail. Both the buttstock and handguard were sprayed with high quality satin lacquer. That light refinishing was all that was needed to make them look amazing.

Just as I wish I would have beveled and rounded the reloading port area before sending to WMD for coating, I wish I would have thought through the barrel length thing and also brazed on a front bead mount. With the insanely slick WMD coating, I could not use regular brazed sights and instead had to use a long Williams shotgun sight pipe with VHB tape which has held. Seems pretty well stuck after testing with a few boxes of shells.

This is a blast to shoot, handles great and the crisp and true crown seems to pattern really well for the point blank to 35-yards with various birdshot and buckshot out to 50-yards. Though I don’t expect to shoot an abundance of slugs, 4-inch 50-yard groups seemed consistently easy and my stick on front sight ended up closely zeroed. With the new action and recoil springs and friction rings, the recoil was very well managed by the A5 design to be one of the softest shooting shotguns available and then there it the fact that it remains an insanely fast cycling that will float five empty hulls in the air before one hits the ground.

I own and review many shotguns which most would consider some of the best modern shotguns on the market, however there is just something so cool about shooting something that was designed and patented over 120 years ago and produced nearly 100-years ago that still feels every bit as modern as the newest shotgun available. The sound, feel and cycling of the A5 is really unique and the cycling speed will give my Mossberg 940 JM Pro a run for its money. 


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Saturday, March 19, 2022

The NiBx Browning A5 12 Gauge - Resurrecting a Legend - Part 2

The NiBx Browning A5 12 Gauge - Resurrecting a Legend - Part 2

In Part 1 of my Browning A5 resurrection, I updated the 1920s vintage Browning A5 with the Browning Speed-feed capability for faster and smoother reloads and cycling and added some magazine capacity in the form of a Nordic Components MXT tube extension to a 9 +1 total capacity.  All the upgrades tested out perfectly, however I knew there was more that could be done to update the nearly century old Browning.
For this upgrade phase, I decided to update the front sight bead to a high viz model and update the steel and metal finishes to update the looks and improve durability for another 100-years and do a little light cleanup on the furniture. THe Part 3 final build tackles the stock finish and transforms it again into something new.
These days, a fiber optic sight has become standard equipment on most sporting shotguns. I elected to get all crazy, loosen up the purse strings, and added a $7.19 Marbles Expert Shotgun Red Fiber Optic Sight. This metal housing sight is well constructed, but extremely affordable. 
The Marbles Expert Shotgun Red Fiber optic sight threaded right into my Lyman Adjustable choke and gives me something to stare at and mentally reflect on, after I miss all the clays that were just thrown for me.  I know some are not big fans of even using the front bead, however I have found that if you are shooting at really close static clay pigeons, such is the case in many competitions these days, it can be a handy reference point. For under $10 it was a worthwhile investment and for me, it improved my hit ratio a bit.
Now that I was considering the WMD NiB-X coating, I stared at the uber ugly corn cob Lyman adjustable choke and then stared at it some more. I must have gone back and forth at least a dozen times on whether to convert to screw in chokes after completing Part 1 of the updates going so far as to break out the torch only to put it away before desoldering the choke. The question loomed on whether I should convert over to screw in tubes.
Although I am not a huge 3 Gun or clays competitor, I do see folks swapping out chokes in competition on a regular basis to combat winds and provide improved patterns at larger distances. This is the sweet spot for this Lyman monstrosity of a choke which allows fast and easy choke pattern changes with just a few spins of the choke. Keeping it, also saved me about $200 in gunsmithing to convert it over to screw in chokes which would have been a purely esthetic decision. With the WMD NiBx coating, the once ugly choke actually looks pretty steampunk cool now. Now I am thrilled with the looks and the NiB-X actually improved the patterns on the choke. I could not be happier and I have something unique that no one else has.
Like most affordable Browning A5 12 Gauge shotguns, this auction find picked up for $200 had finish issues. A little surface rust here and there, some ugly spots, and a lot of areas which really necessitated the A5 getting a full re-blueing.  I had done this laborious sanding and polishing task with my old Browning Sweet 16, the A5 12Ga little brother, and was not in the mood to do that task again; especially for a working shotgun. The WMD NiBx (Nickel Boron type) finish for $200 seemed like a huge time saver which offered a permanent solution to rust and corrosion and added operational lubricity as well. I was sold on the WMD finish after my purchase of the MarineCoat Barnes Precision AR15, however any firearm can benefit from the coating; even this old Browning A5. It was the right decision and I even did an old H&K P7 with the process as well.
The biggest update to looks, durability, operation, and reliability was definitely sending almost all the metal parts off to WMD Guns for their NiB-X coating. Actually, the only metal parts that did not get coated were the small pins, screws, and the bolt assembly simply because I could not get it fully disassembled which is required for the treatment.  
Even after bending three punches I could not get a couple of the pins to budge on the bolt, so a portion of the bolt was the only metal left untreated with the WMD NiB-X coating. I dark blued the bolt and reblued the screws and pins to add a nice color contrast against the Nib-X coating.
The WMD Guns NiB-X finish is roughly similar to NP3 or Nickel-Boron (Ni-Bo) finishes, however WMD’s proprietary Nickel-Boron finish (includes Teflon) adds a huge amount of lubricity and ups the durability as well. 
This was a $200 upgrade. Disassemble all the parts, package them up and send them off to WMD for coating. In about 60 days, you will have all your parts back fully NiB-X coated. They treat both aluminum and steel the same, so even if you have steel gun parts and an aluminum extension tube they come out the exactly the same finish. In this case, the parts came out unbelievable and looked factory new after the process
Honestly the most difficult part was not the disassembly, but actually the re-assembly. I must have watched the initial noted disassembly video fifty times to get all the pieces back into the A5 and working correctly.
For this resurrection of a firearm nearly a century old, the silver/grey finish was a huge update to looks, however the WMD treatment does so much more. NiB-X finish that will resist scuffs, wear, and moisture, minimize cleaning and lube requirements, and give your action a noticeably smoother feel…permanently.
The net result of the treatment was a gorgeous factory new looking Browning A5 which anyone could swear just rolled out of a high tech 1920’s factory in Belgium.  The finish is amazing, eye-catching and also very very slick. I would say that the newly treated parts are nearly twice as slick as they were previously and tuning of extra-light, medium, and heavy loads with the friction ring juggle was far less sensitive and required less lube for reliable operation.  All around much more than just a pretty finish upgrade.
There is no doubt that this redue has the same appeal to many as a taking a beautiful classic car and then hot rodding it, but hey they made like 3 Million of these A5s. In fact, estimates are that this old Browning A5 is circa 1920s which puts it well into the vintage category of firearms.  I was thrilled to be able to breath new life into this nearly 100-year old but fully functional gun with a little TLC and a few upgrades.
I have run around five boxes of 2 3/4" shells through the updated WMD coated A5 and it seems to be much faster cycling after the NiB-X treatment than before and is certainly exponentially smoother cycling. The coating of the Lyman variable choke also seems to have tightened my patterns a abit as well; perhaps because it smoothed and slicked up the choke.
Of note, there are three different tuning positions the recoil and friction rings can be placed for different load powers. The lower power clays loads used extensively in clays, 3Gun competitions, and upland game hunting were very reliable with my previous "medium" tuning spring setting, however lubricity of the WMD NIB-X finish definitely provides a wider reliability range on each each tuning stage without running the spring really wet with lube.
The WMD NiB-X finish is top notch and consistent even among aluminum and steel parts and my little fiber optic Marbles sight has really helped my clay busting game.  The only update that is left which needs addressing are the worn stocks which either need a finish refresh or new stocks completely - Stay tuned.
This A5 is set to deliver another 100-years hunting and clay shootings. After all, given the technology John Browning used on this original design, I am sure he would celebrate these high tech upgrades to his classic design.


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The Browning A5 12 Gauge - Resurrecting a Legend - Part 1

The Browning A5 12 Gauge - Resurrecting a Legend - Part 1

The Browning A5 shotgun is a stunning achievement of engineering and in fact John Moses Browning noted the A5 was his best achievement as the first ever semi-automatic shotgun. The A5 and later the military and police focused A8 were named for AUTOMATIC 5 Shell (4+1) the A8, AKA Rhodesian, was a 7+1 capacity. It was patented in 1898 and first produced in 1920 until 1999. Over 3 Million were produced. It remains one of the highest production shotguns ever and likely one of the more complex.

Disassembling the Browning A5 will confirm the genius of the design and confound most armature gunsmiths, but shooting a properly setup A5 will deliver the fastest and softest shooting shotgun of anything still on the market. People are still shocked how fast A5s will cycle. It was and still is a revolutionary design which still outperforms many, if not all, new shotgun designs. Not only does the shooter get a softer recoil of a semi-auto bolt on the A5, but the long-stroke barrel recoil design which reduces recoil further with the barrel moving with the bolt backward during cycling. Admittedly it is not a light shotgun which helps dissipate some additional recoil. The result is a very soft shooting shotgun. The downside of course is that the Browning has well over 50% more parts than a Benelli, Remington, Mossberg, or really any modern shotgun, but those parts do things that the new guns don't. I wanted… no, I needed a high capacity Browning A5 12 gauge. This has been an ongoing project that has taken some interesting turns which started with these 3Gun style mods.
I am a huge fan of the tank-like durability of the Browning A5 design and have been shooting a Belgian Browning Sweet 16 since I was barely walking.  Yes, I am of the belief that there is no quality comparison between the finely made Belgian models and the bastardization that the Japanese factory delivered labeled as a Browning. Lately though, 16ga shells have literally been impossible to find, so I have kept an eye out for a good deal on a 12ga Belgium Browning A5.  
In good condition, an A5 can run as high as $1000, in excellent condition quite a bit more.  $600 will usually give you a well worn A5 in working condition with the updated speed-feed and maybe fitted with screw in chokes, but they will be nothing pretty to look at. After over three years of being patient, my gun dealer had a very old estate auction specimen in decent condition available for only $200 complete with smooth top barrel and beautiful furniture.  I would have liked to have a vent rib and screw in chokes, a little less surface rust, higher condition stocks, and it desperately needed a good cleaning, but it worked. Why only $200? Sadly it featured a very old Lyman adjustable "corn cob" choke which killed the value. Adjustable chokes are great from a hunting perspective and most will agree they work awesome, but look like hell and always cut the value in almost half. The other part of that price was it was very old Gen1, which meant some unique features.
When I say this was an old A5... I mean like 1920s, nearly a century old Browning A5. Due to the age, it had the pre-speed feed one-piece-shell-lifter which meant that loading required pushing the bolt release button for each shell loaded - a total pain in the butt.  The lack of the very cool and fast speed-feed feature, meant goofy two handed feeding requirements, plus the 2-shell magazine limiter, were big bummers for a gun I was transforming into an awesome fast handling 3-Gun shotgun. But... “Gentlemen, We Can Rebuild this Browning A5. We have the technology. We have the capability to make the world's first 3 Gun A5. This A5 will be that machine. Better than it was before. Better. Stronger. Faster... and hopefully even sexier.

OK, yeah I was not attempting to make a six-million dollar A5 and this is almost certainly not the first A5 used in 3 Gun or Sporting Clays competition. Once I placed the Browning on the stretcher and had the guts all pulled apart for a deep cleaning, I decided it was time to add in a list of updates including a 2-piece lifter and speed feed conversion, increasing the magazine capacity. Let’s get through the first of multi-part upgrade.
The earlier initial versions of the A5 had a front trigger guard vertical sliding safety and the one-piece lifter. The next newer GEN2 A5 version included the Speed-Feed feature and moved the safety to a tradition button cross-bolt location at the rear of the trigger guard. This old specimen is vintage and had the front trigger safety and the one-piece lifter.
The speed-feed is a very unique feature in the world of shotguns. With the bolt locked back, you can just feed rounds into the magazine, the action will recognize the magazine not has a shell and will close the bolt and autofeed that first round into the chamber and boom you are shooting again. None of that goofy one round in the breech, hitting the bolt close button and then worrying about feeding the magazine tube. On an A5 with auto feed, you just feed the beast right into the magazine tube and you keep shooting.
There are actually two big advantages of the Speed-Feed upgrade. The first is that it allows the Browning to be loaded fast when empty - push a shell in the mag tube and the magic of Browning's machine chambers it at the speed of light. Doing the conversion is a huge speed and ergonomics update.
The Browning locks open after the last round is fired, which provides the auto-loading benefit of the Speed-Feed feature.  This allows very fast reloads especially if you just emptied your gun and only need one or two rounds to finish a stage. As a lifelong Browning shooter, I am always stunned on other guns; “what do you mean I need to feed and rack or close the bolt?”

If you get lucky enough to obtain a A5 in good condition with this feature, rejoice and be happy, if not, luckily the older version’s feeding can be easily upgraded with four key parts ($129 factory drop in parts direct from Browning Service). You will still have to manage with the sliding safety unless you upgrade the trigger housing as well… easily another $150 in parts, but doable.  Surprisingly the four Speedfeed parts upgrade is easily if your screws have not all rusted tight. In that case, turn it over to a gunsmith who will charge around $100 to install your parts. My A5 came apart easily and I had the updated 2 Piece Carrier Assembly, Carrier Spring, Carrier Latch, & Carrier Latch Spring swapped in about 30 minutes including watching the below well done disassembly video - 

If you are comfortable building an AR15, then you can complete this update.
Required parts from Browning Service/Parts - 50440-B1111064 - 2 Piece Carrier Assembly 12ga, 50467-B1111107 - Carrier Spring, 50537-B1111269 Carrier Latch, 50540-B1111277 Carrier Latch Spring - $129.
Some say this conversion requires fitting. My parts dropped in without an issue. I do know that fitting is required for the 16 and 20 gauge model as there are none of these parts left in existence.
The Carrier Latch Assembly which is a flat lever contraption with a flat spring attached on the internal side of the receiver area with a tiny flat-head screw pin uses the staged round to push a catch to prevent the next round in the magazine from double feeding. There are still only about $20 new-old-stock, so if you can always replace it. Many times the magazine catch portion gets bent flat over the years and needs to be bent back to its original position which should be flat with the inside bore of the magazine tube. If you cannot hand feed the A5 without jams, or it double feeds while shooting, chances are very high this is the culprit not the recoil springs. These are one of the parts that can requiring some tuning to get the timing and magazine spring tension of the next round right for reliable operation.
I love the innovation of Nordic Components and it was no surprise to me that they offer one of the only Browning A5 MXT magazine tube extensions.  These kits include the nut and spring which can add +1 to +9 rounds depending on the length you select. This is a simple upgrade; unscrew the existing magazine tube cap and screw on the Nordic MXT tube extension with the included spring. In this case I added a +6 extension which updated my A5 to a 9 +1 total capacity with 2-¾” shells. Note that if you want to swap back to hunting 2+1 hunting capacity, all you need to do is remove the tube and reinstall the original spring, limiter dowel, and handguard nut and you are back in the hunt.
Two big tips when installing the tube and 4 foot long magazine spring. First wear safety glasses. Second, read the directions regarding trimming the spring, and third, place a 1/4" dowel rod in the magazine tube, thread the spring on, and then the Nordic extension on with some of the dowel exiting out the end of the tube. The Nordic extension specifically has a hole in the end of the extension for this spring install method. Screw the extension in place and pull the dowel out. This method will keep the spring in line throughout install, keep the cursing to a minimum, and save about 500 calories from chasing a spring around the room. I did buy the clamp on Nordic picatinny and QD swivel, however since the A5 barrel recoils and moves, you cannot use it like it was intended.
I really went back and forth on whether to keep the adjustable choke or convert over to screw in tubes. Many consider an adjustable choke a huge feature for a hunting shotgun.. I am a believer. They are one of the simplest choke tube devices on the market with no barrels to swap out or chokes or wrenches to lose or store. That noted they look horrible and this permanently mounted Lyman “Corncob” version is among the ugliest yet with the expansion chamber brazed in place. Despite its looks, the expansion chamber and compensator was marketing as a recoil reducer. Without a direct comparison, it is hard to say for sure.
Although I am not a huge 3 Gun or clays competitor, I do see folks swapping out chokes in competition on a regular basis to combat winds and provide improved patterns at larger distances. This is the sweet spot for this Lyman monstrosity of a choke which allows fast and easy choke pattern changes with just a few spins of the choke. Keeping it, also saved me about $200 in gunsmithing to convert it over to screw in chokes which would have been a purely esthetic decision. In Part 3 years later, the last update, this choke did go since the barrel was chopped to a 18.5-inch length and I could not be happier.
There is no doubt that this redue has the same appeal to many as restoring a classic car. In fact, estimates are that this old Browning A5 is circa 1920s which puts it well into the vintage category of firearms and likely a $2000 gun restored with an appropriate vent rib. Whatever, they made 3 Million of these, and I was thrilled to be able to breath new life into this nearly 100-year old but fully functional gun with a little TLC and a few upgrades.
So how does it all work? Awesome! Like any Browning A5, you do need to lube down the spring and friction rings and assure the friction rings are tuned/placed in the correct position for your load. I have run a few hundred boxes of 2 3/4" shells through the updated A5 and it works just like any of the updated speed-feed A5’s do. A great deal and a fun project which still has more surprises around the corner.


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Tuesday, March 15, 2022

Troubleshooting Your AR Build

Troubleshooting Your AR Build
At this point I have completed hundreds of AR builds from standard .223, 5.56 Nato, .223 Wylde, 5.45x39, 9mm, 10mm, and even a few in the 308 and 7.62x51 chambers. I will say none have gone together perfectly however a few tips and tricks along the way have helped me get a bit smarter with each build. Experience does breed success and thus the reason I generally believe a defensive firearm you will bet your life on should be built by a professional. Following are a number of tips and tricks which in sum should resolve or prevent the vast majority of AR format functioning issues.
The AR format is by its nature a much more complex machine with more design similarities to an engine than a bolt action rifle. The gas pressure operated system can be a bit finicky and can also be the main cause of problems.  Including myself, many an expert has professed the reliability improvements of heavy buffer springs, carriers, and buffers, however now with more experience, I have seen that these are just band aid solutions to an over-gassed or poorly designed gas system or poorly tuned rifle. Other times, problem resolution can be as simple as just swapping out a magazine or part, so lets take a look at some best practices to avoid problems in the first place.

A lot happens as the trigger is pulled, the hammer drops, hits the firing pin which sets off the primer and charge. The pressure in the cartridge pushes the bullet down the barrel and after the bullet passes the gas port, gas is leached off and blown back into the bolt via the gas block, gas tube, and gas key on the carrier. Pressure increases and pushes on the gas seals in the bolt which unlocks the bolt and cycles the action.  A lot can go wrong in that entire process.

Always keep in mind that the AR15 was designed to run with a 20” barrel with a rifle length gas system and full rifle length buffer tube, spring and longer & heavier buffer. By moving to a shorter carbine gas system and buffer tube assembly we are not exactly helping improve performance, recoil, or reliability but instead making it harder for the system actually do its job in a shorter overall system. The shorter the overall rifle system, the harder it is to tune for reliable operation.

For a new AR builder, I would stay away from piston systems until you have some build experience or purchase a complete working upper or complete factory rifle. Superlative Arms makes incredible system that is amazingly reliable, however for the less experienced builder a gas impingement system. For the scope of this article, I will focus on standard AR15 style direct Impingement gas system rifles as they are far more popular for the masses.
A typical builders kit without a stripped lower
One of the most common causes of problems on the AR format are those related to the gas system. Too much gas ends up battering both you and shortening component life, but too little affects functional reliability with a rifle that sometimes cycles.
Too Much Gas - An overgassed/high gas pressure driven system is generally balanced out by heavier components at the breech end to slow the cycling down. The result is that we upgrade from a standard buffer to a heavy “H” marked buffer, heavier “H2”, and even very heavy “H3” buffers and marginally heavier M16 bolt carriers.  
There are even heavy specialty buffer springs available. All we have done is increase the reciprocating mass to the point where the gun cycles properly and less violently. Sure the heavier components balance things out, however too much hot gas means more overall stress on all components and more dirty hot gas in the action which equates to a hotter and dirtier gun; not to mention an overall heavier gun in the process.

Cause - The cause is usually an oversized barrel gas port diameter due to a “better safe than sorry” manufacturing model of most barrel companies. The thought process is that too much gas pressure will always function, to little could cause functioning issues with certain components.

Solution - A solution is the above heavier BCG, buffer spring, and/or buffer, however the best solution is to control the gas pressure in the first place with an adjustable gas block such as those from Superlative Arms. I stand by the comment that this is the single best upgrade you can make  to an AR15. Recoil, muzzle rise, component wear, and filth all go down and the rifle runs a little cooler and cleaner. Once you are able to control the gas pressure, you can do some really cool things like further reduce gas pressure when using a lightweight BCG from YM or JP Rifles or others with a standard buffer all without affecting reliability. 
Adjustable gas block are the key is to bring things in balance. See my Adjustable Gas block article here for tuning how-to. Basically keep reducing gas pressure with your lightest load until the bolt does not lock back and then increase the pressure setting by a quarter turn. The need for a heavy bolt carrier is instantly myth busted once your are able to adjust the gas pressure and balance the system.
Too Little Gas - This will cause short stroking, double feeds, failures to feed/extract/lock-back, and stovepipes.
Cause - System diagnosed as under-gased are usually the result of improper assembly, however binding components, too heavy of carriers, springs, or buffers or other design issues can exaggerate or imitate an under-gased system. There are certainly fixes which do overcome many design or functional issues caused when fielded, however addressing the root cause is the best route to a durably reliable AR.
Solution - In almost all cases the gas block is not pushing full pressure. Usually the gas block is not aligned to the gas port in the barrel or has been mounted crocked. Sometimes it is canted or has moved from gas pressure and/or has not been secured properly. In some situations I have seen out of spec gas blocks which can leak pressure. 
Usually the perfect gas block placement is not slammed against the turned edge on the barrel, but sometimes it is. Drawing a center-line down the barrel with a pencil can help with alignment. Disassembly and reassembly with a set of calipers to measure where the hole is on the barrel in relation to the hole on the gas block. Remember usually the rearward most retainer screw on the gas block aligns with the inside hole in the gas block. Worse case I eyeball the alignment based on holding the gas block next to the barrel and lining up the barrel and gas block ports. One trick during assembly is to install the gas block upside down before installing the gas tube to find the exact positioning of the gas block from the shoulder on the barrel.
Smooth Movement - An easy quick check after each cleaning is recommended. Occasionally you will have a BCG that binds for one reason or another which definitely affects functioning. Point your unloaded AR upper skyway and bounce the bolt up and down in the receiver a couple time to simulate cycling. This simple little test will tell you if something is binding. Rarely you might have an out of spec carrier, or loose gas key (seen this more than you would think), but it could also be some junk or a partial brass case stuck in the receiver.  Clean it out and replace parts as required.

Bad Seals/Rings - Rarely an issue. Those little rings on the bolt do wear out eventually or can become aligned in such a way that they will leak.  Assure all the cuts are not aligned and/or replace as necessary. You should be able to hold the BCG vertical by the bolt and the tension of the rings should not allow the bolt to extend under the weight of the carrier.
Ejector Tension - Generally a problem that will have even the experienced guys in the crowd throwing their hands in the air and selling off a great gun. Brass should eject at about 2-3 o’clock and about three feet from the side of the gun. If they are hurling 10+ feet away and you start to have feeding/functioning/ejection issues about halfway through the mag, then an over-tensioned ejector is probably the issue.  The military went to a higher-tension/stronger spring to improve full-auto fire functioning with M16 carriers, however in most cases too strong of an ejector spring will not allow a round to properly feed on the bolt face and/or from a timing perspective cause the cases to attempt to eject before they clear the port. The result more often than not are double feeds or failures to fully or partially eject. Most people think they need a stronger spring if they see this and it is usually quite the opposite.

Solution - If the ejector cannot be pressed in slightly with the fingernail into the bolt, then it is probably too tight. Another test is to remove the bolt and place an empty case in the extractor lip and lever it down on to the ejector; in some cases I have seen that the ejector is so strong that the extractor cannot hold the brass in place. Remove the spring and either grind it down or swap to a shorter ejector spring or just replace the entire bolt if you are lazy. I know the DPMS 308’s have two different ejectors; one version puts way too much tension on the same spring length. The general rule is that if you cannot re-install the ejector without using a tool to push it in, then it is too strong.
Loose/Leaky Gas Key - More and more an issue with crappy import carriers hitting the market. Gas Keys do come loose rarely on quality carriers. Inspect the carrier end-to-end during cleaning. If it is loose, use permanent Loc-tite (Permatex gasket sealer is Mil-Spec) and tighten it back down.
Bolt Bounce - This is a situation where the bolt bounces slightly after it chambers a round because the bolt is moving too fast due to excessive gas pressure and/or to strong of a buffer spring. Without super high speed video equipment, this almost impossible to witness with the naked eye, however it can occasionally be experienced during really fast shooting. This is experienced in the form of a failure to fire with the hammer dropping. Basically it is a timing issue when the bolt is bouncing out of battery at the moment the hammer drops and the firing pin hits air or a partially chambered round. If you are seeing bulged cases at the bases or nice heavy primer strikes on the primers and then a light strike and failure to fire during high rate firing, then you may have a bolt bounce issue.  The solution is to move to a heavier carrier or buffer or reduce the buffer spring tension or gas pressure level with an adjustable gas block. Generally the adjustable gas block is the easiest and least expensive solution. The faster the bolt goes back the faster it wants to return.
Bolt Not Locking Back - Could be a lot of things. Usually it is just a bad magazine spring that is not pushing with enough pressure to engage the bolt stop. I have also had some issues with Strike Industries and some other aftermarket bolt catches. I forget who offered at one time a heavy duty bolt release spring, but that is just idiotic and would then need to compete with the magazine spring tension to function correctly.
Check the gas block alignment and assure there are no gas tube obstructions. Stick the straw of a WD-40 can down the gastube and if it comes out the barrel roughly the same rate as your are spraying it then you are OK in most cases. What to watch for is WD-40 sprayed in one end and it dripping slowly out the other. If so check the alignment and gas tube. 
For the most part, AR15s, especially carbines are seriously over gased to the point most will run even if half the tube or port is covered. The most common problem is that the gas block is not even close to being properly aligned with the barrel's gas port.  A builder could also have the rear vent hole sealed on the back of the buffer tube creating a weird pressure situation with some buffers. 
 A2 builds I have seen this and even done it myself where I installed a longer 308 buffer and buffer spring by mistake - on a AR15 build which will physically not allow the bolt to lock back. Similarly installing a rifle length buffer and/or spring in a carbine or an H2 or H3 buffer which can retard the bolt so much that it cannot fully cycle or lock back. See the buffer weights and measures data below to the right buffer components.
One part which has given me problems is actually the bolt catch. I have installed and tossed a couple out-of-spec loose bolt catches including fancy aftermarket versions. If the bolt catch is not decently tight fore and aft, I have had issues with them not catching a bolt on occasion.
This may seem like an obvious step, however I have caught more issues in this step than any other just with close examination of an empty unloaded AR all under the assumption that “Stuff works loose.”
Assure the flash-hider, buffer tube castle nut are both tight and secured with Loc-Tite. Are all the pins and detent present, does the trigger function correctly even when holding the trigger down and hand cycling the bolt to imitate the next round cycling? When you point the muzzle skyware on a separated upper receiver, does the bolt float effortlessly without bind as you bouncing it up and down into the chamber by hand?
Typically builders get all emotional about what they want based on whatever their buddy or the latest expert recommended, however the reality is that most of the components do not increase reliability, but some do such as an adjustable gas block. Stick with Mil-Spec components if you are focused on reliability as high tolerance “3-Gun” performance parts may throw off the operational balance of an AR without a little tuning/tweaking.
In general every upper or lower receiver I have ever tested has functioned perfectly. The upper or lower receivers have never been a root cause of any issue I have ever experienced, nor the buffer tube, gas tube, stock parts kit, or the furniture, so choose what you like.I will note that I have had friends buy some real warped uppers that still even worked well.
Barrels for the most part have not delivered issues themselves regardless of chambering or the finish of the feed ramps, however gas port diameters do vary which can create gas pressure issues. From my experience, pressure problems related to the barrel and gas block have been responsible for well over 95% of my functional issues. The other 5% of issues can usually be tracked to the buffer spring and buffer rates and weights.
AR15 RIfle - Buffer 5.2oz, 5.905” - Spring 44 coils, uncompressed 12.75”
AR15 Carbine - Buffer 3.0oz, 3.25” - Spring 39 coils, uncompressed 11.25”
AR10 Rifle - Buffer 5.4oz, 5.215” - Spring 34 coils, uncompressed 13.75”
AR10 Carbine - Buffer 5.4oz, 3.26” - Spring 34 coils, uncompressed 13.75”
DPMS 308 Rifle - Buffer 5.3oz, 5.31” - Spring 39 coils, uncompressed 12.75”
DPMS 308 Carbine - Buffer 3.4oz, 2.48” - Spring 27 coils, uncompressed 11.5”
AR15 Carbine Buffer Weights - STD 3.0oz, H 3.8oz, H2 4.6oz, H3 5.4oz
Note - Super special extra heavy buffers (H2, H3) and springs have caused me nothing but problems with anything but full power Nato spec ammo.
80% of the time it is ammo or magazine related.
If you do have issues, try swapping not only the magazine, but hte magazine brand and also ammo. A lot of times you have a magazine that is ready to retire or crappy ammo causing the issues.  As noted before, it likely is due to overgased pressure, improper buffer weight or spring, or a extra power ejector. Sometimes the barrel extension and Receiver Feedramps don't match up well - a little dremel polishing (none abrasive) goes a very long way to smooth things out.
A general formula for barrel/gas system configuration is: sub-16” barrels should have carbine gas systems, 16”-18” barrels with Mid-Length gas systems, and 18”+ barrels with rifle length systems. Obviously there is some leeway, but a 20” barrel with a carbine system will probably be way over gassed and a 16” barrel with a rifle length system will generally have some under-gassed cycling issues. Ballistic Advantage and Feddersen based barrels do offer tuned longer gas systems, however with some heavier carriers or higher power triggers, I have had issues.
Even with a properly designed system an adjustable gas block will help you fine tune the system. Once properly tuned, it will deliver you a stunningly near recoilless and reliable shooting rifle all without adding weight to your action or without changing any other components.
Grip Spring & Detent - Almost every AR owner at some point swaps their grip, however nearly every grip swap virgin usually also ends up on all fours looking for the grip spring and detent after pulling off the grip. … and then ends up having a crunchy sounding selector when reinstalled.  It should be noted that the grip itself partially holds the spring for the selector switch and the other half of the spring extends up into the selector detent hole pressing against the detent. Watch how it comes apart and prevent either crushing the spring during install or the dreaded boing of the spring across the room. 
Generally I have not had any problems with USA made Surefeed steel, stainless, or aluminum magazines or with MFT Mission First and Magpul’s polymer mags. Other mags work well also, however I would note caution as there has been a flood of really crappy mags hit the market which I personally would run from. I had a HUGE issue with literally a case of the shown Troy mag feed lips expanding to the point of dumping rounds. European mags are less forgiving than US mags as they adhere to a very tight tolerance level. Most 30-round Euro mags, such as E-Lander, are designed for a standard 28-round military spec magazine load to assure positive reloads on a closed bolt.
As any military trained person will tell you they only load 28-rounds in a 30-round mag just to assure positive reloads. USA mags in general are designed around the “US consumer” expectations to load a full 30-rounds, however the Euro mags are not. Also euro spec AR15 receivers are less sloppy than to what many US manufacturers adhere to, which in the end means that a Euro mag may be a bit too tight to properly cycle. Be safe and load 28 and you will have far less issues overall with any mag you use.
First and second generation DPMS 308 factory mags are specifically problematic and contribute greatly to feeding and functioning issues. With a few modificaions they can work fine, however in general, I have swapped to Magpul LR-20 magazines which have resolved a great number of 308 related functioning issues.
The net is don't by crappy magazines. Buy MFT, Magpul, Lancer, or Surefeed.
Some ammo is shit and will cause feeding and functioning issues. Specifically, I have tested and proven to myself that Herter’s 62gr .223 Remington rounds are underpowered. If you want to have a bunch of jams, but this stuff. In most other cases, I have not had any significant issues with any other ammo. My favorite plinking/fun ammo has become the American Eagle 55gr and Hornady Steel case, Frontier, and Black ammo.
If you are building your first rifle build it based on standard everything. If it was me I would buy an Aero Precision Builder or Ballistic Advantage set, perhaps one of the monthly limited edition cerakoted sets, a Aero parts kit, AP or BA barrel and start building. Really for the price, I probably would just buy a complete upper from Aero or BA. Faxon also makes great problem-free barrels. My hope is this prevents some great ARs from being sold or pushed to the back of the safe.

Of course you will need parts and there is no place better to buy than at