Monday, January 21, 2019

PWS MOD2 Custom Direct Impingement AR15 Pistol Build


PWS MOD2 Custom Direct Impingement AR15 Pistol Build

My all time favorite AR15 based firearms are the super trick looking lightweight forged MOD2 AR15s from Primary Weapons Systems. These long-stroke piston guns have delivered several thousands of trouble-free rounds without maintenance or even a drop of oil and they just keep running - neglect which a DI gun will not accommodate. PWS is most notable for being the long stroke piston operated AR-15 manufacturer and one which heavily emulates the functionality and reliability of the AK-47. The PWS Mod 2 long stroke gas piston system is absolutely incredible and arguably the most reliable AR15 format system made with quality surpassed by none, but I already have two of those and wanted to do something a little different the third time around with just their receivers.

With a sub-MOA premium stainless match grade Ballistic Advantage Hanson barrel in hand, what I really wanted to build a direct impingement gun for my third PWS based gun. PWS only sells piston systems and stripped lower but not their lightweight uppers. Luckily they have a sister company named Bootleg Inc which provides PWS upper parts for the direct impingement market. The result is that you can cobble together a PWS DI gun even though they do not make one. The lightweight forged upper and handguard are both Bootleg parts and the lower receiver is a PWS MOD2 stripped lower. 

PWS Receiver and Handguard - The handguard, upper and lower receivers, and CQB muzzle brake are all PWS. The PWS MOD2 MK107 receivers used for this build took all the great things about the original PWS MOD1 series pistols/rifles and built on top of that with refinements and additional weight savings through some creative engineering. For example instead of cutting a bunch of holes into the receiver to drop weight they designed the deep weight reduction reliefs into their own proprietary forgings while not opening the internals of the rifle up to dirt. 

Yes I did say forgings. The receivers on this firearm are not mil spec receivers PWS has milled down nor billet that has been milled. What we have here is a custom forged upper and lower made from PWS’ own proprietary forgings which come out of the forgings with all the reliefs you see featured. For the record that is a very expensive manufacturing path to develop proprietary forgings, but forging does deliver a stronger part pound for pound vs billet. Forged receivers by their nature are inherently stronger than billet due to hot metal grain structure flowing and aligning to the forging. 

The final metal grain structure is not linear, but instead flows with the contours of the shape which in theory delivers a stronger and more durable part. In the process of strategically lightening the receivers they ended up looking amazingly cool. The lower receiver features an integrated trigger guard, larger flared magwell, and inlets for all the extra ambi-parts. The upper receiver has been trimmed down though the reliefs, but also lightened with the omission of the forward assist. Other nice touches are beefing up certain areas to increase strength such as near the barrel extension union on the upper and also adding a captured ejection port door pin.

To assure the Ballistic Advantage Hansen Profile Match Grade ⅛ twist .223 Wylde barrel’s bark was redirected away from the shooter, a PWS CQB brake was attached. I have used this brake on many firearms over the years and personally believe any AR or AK intended to be shot indoors or adjacent to other shooters should not be without it. Only light earplugs are required for comfortable prone shooting all day. There is magic within that CQB flash hider that I have not found any other muzzle device to deliver. For short barreled guns, the flash hider seems to magically push sound away from the shooter.

The ultralight slim PicMod handguard is yet another PWS innovation which delivers standard picatinny rails which are also KeyMod compatible - Genius! PWS was able to also skim a few more ounces out of the new handguard design. The slim design also sucks in any attached lights into a narrower profile which limits snags.

Ballistic Advantage .223 Wylde Premium Series Barrel - This special .223 Wylde chambered 10.3 inch barrel is machined from 416 Stainless Steel with a bead blasted finish, Nickel Boron Coated Extended M4 Feed Ramp Extension, a proprietary BA Hanson tapered profile, match cut crown, and include a pinned lo-pro gas block. One particular note is that BA tunes their barrel gas ports to cycle reliably without being overgassed and assure this perfectly tuned function with an included gas block. The BA gas blocks are both screwed and pinned for reliable operation which will never loosen. The advantage of BA’s smaller gas port tuning on the barrel is that you really do not need an adjustable gas block to moderate an otherwise overgassed system, but the disadvantage is that these softer recoiling barrel gas ports are not designed to work with aftermarket piston kits as this usually require a bit more gas to operate. 

Over the years I have been writing for BA and using their barrels, they are definitely among the top tier of production AR15 barrel manufacturers and the Premium Series have always delivered sub-MOA. A great example here is that this 10.3-inch barreled rig with just a 1-5 Sig Optic delivers .75-inch 100-yards groups and 1-inch 125-yard groups all with just 40gr Fiocchi Vmax bulk pack rounds I use for predator hunting. If fed the really top tier match grade ammo from Hornady, Federal or Black Hills, the groups shrink further under .5-inch.

Sharps XPB Carrier Group Complete in NiB-X - Plainly put, this is the most technically advanced Bolt Carrier Group available anywhere for the AR15. Sure JP, YM, and Barnes are all the reining top tier Bolt Carrier Groups made with a precision not found elsewhere, but the Sharps XPB takes it a few steps further. In addition to the high precision, XPB adds a whole lot of design and technology upgrades. The Sharps BCG starts with full super premium S7 steel for both the carrier and bolt, 4120 and 4340 steel for pins, and then tested with MPI and HPT. The entire design is float balanced for optimal neutral weight shifting during cycling to deliver a smoother and more reliable cycle. Then they NiBx (Nickel Boron Teflon) coat everything for a self lubricating function. The included Sharps ReliaBolt delivers a design optimized for reliability performance beyond the design capabilities of typical AR15 bolts. In short, if you are not running a piston gun and still want extended operation beyond normal maintenance cycles, then you really should be running a ReliaBolt.  Well worth the $189 Sharps is asking for these complete XPB BCG.

Law Tactical Folding Adapter -  The Law Tactical AR15 Folding Stock Adapter transforms that short little high performing AR15 pistol into something ever shorter that can easily be slipped into most backpacks. The Law Tactical AR15 Folding Stock Adapter effectively allows that pesky buffer tube to be folded out of the way when not in use. Great even on stowable rifle, the Law Tactical Folding Stock Adapter can be used on any AR15 or AR10 rifle to reduce overall transport length which made it perfect to slip into our Sneaky Bag.

My other two nearly identical MOD2 PWS pistols were equipped with Maxim braces. These are super cool, look really trick, and functional, but cold steel rods also are not super comfortable to check weld up to and lay down behind for extended periods on a ice cold hunt. The Maxim braces also are longer when collapsed than the very packable Law Tactical Folding Stocks which would allow a backpack carry option.

SB Tactical SBM4 AR15 Brace - SB Tactical currently has over a half a dozen different brace options. This one felt like the most comfortable option for a scoped rig that gets shot a lot from the prone position. The SBM4 is SB’s update to the original brace design with an overall slimmer, lighter, and more ergonomic design which slips securely onto any AR15 pistol buffer tube with a light spray of rubbing alcohol and stays put. This is a great option for those that do not want an NFA firearm and retain a pistol designation or those that want to try out a gun before getting married to is with an NFA Tax Stamp.

CMC 3.5lb Flat Bow Trigger - The CMC triggers are amazing and have been for a very long time. The feel of this trigger in this build helps me deliver some rather outstanding sub-MOA groups and full length rifle owner would be proud of. Easy drop-in install makes the CMC triggers one great option for an AR15 trigger upgrade.


Sig Sauer Whiskey5 1-5x20 Optic
- Aftering becoming sold on the value of high quality optics, I am convinced that precision accuracy is more dependant on the clarity of your optics than it is on the gun. Sig Sauer is bringing some phenomenal optics to the market with clarity rivaling optics up to twice what Sig is charging. This $550 street priced Whiskey5 1-5x20 optic delivers stunning clarity and allows me to still easily punch .75-inch 100-yard groups with only 5x magnification - I call that a win.  




For this build I opted for a simple crosshair Hellfire Triplex reticle with center point illumination. I really have no intent to mess with the turrets unless my zero changes considerably from my Fiocchi 40GR VmAx rounds to the Hornady Full Boar ammo. If zero’ed at 100-yards, I can connect with anything between 50-250 yards with less than 2-inch of variance which is good enough and very fast for predator coyote and hog hunting. The Whiskey5 1-5x20 was mounted via a Aero Precision Ultralight 30mm Mount which I found to be one of the best lightweight yet rugged AR15 optic mounts on the market. 

Sneaky Bags 27” SPYDER bag - The SPYDER has the look of a tennis racket bag which makes transport even into after-hunt restaurants low key. Let’s face it, truck cabs off no placed to securely stash anything. The SPYDER was a perfect single sling pack for the fully assembled PWS pistol with 20-round magazine loaded plus offered a ton of storage for up to two PDW firearms, pistols, magazine optics organization and plenty of internal MOLLE and hook & loop for customization. 


Miscellaneous Parts & Cerakote - Other parts included a Phase 5 Tactical ambi charging handle, Magpul Grip, CMMG Pistol Buffer Tube & Lower Parts kit, and KNS Precision anti-rotation pins.  The receivers, handguard, buffer tube, and optics mount were coated with silver grey Cerakote. I certainly could have gone nuts here with all the crazy cerakote jobs now, but I wanted a greyman type gun which was subtly custom without screaming it.

FINAL THOUGHTS
This gun continues to impress me outshooting many full sized AR15’s I own. It really does beg the question why I would want a larger gun. As a strong skeptic of AR15 pistols early on, I now get why so many people like this format. It can be light, fast fun and super accurate.

It may sound a little nuts to us a shorter barreled gun with a bipod, but what I found was that a shorter 10’ish-inch barrel AR15 with stowed bipod is very maneuverable during stalking hunts through tight woods, can still deliver amazing accuracy and energy out to 250 yards, and is a sweet spot for limiting the snap and boom of a very short barreled AR15s. The format also cases and stowes easily and is considered a concealed pistol in most jurisdictions. This transport feature alleviates the fear of leaving the gun in the back seat of the truck to potentially get stolen to and from a hunt. That size is a great compromise for the needs of 90% of shots on hunts where you only have a few hours to hunt. 

BUILD COST

PWS Upper - $180
PWS MOD2 Lower - $220
PWS CQB Brake - $149
Ballistic Advantage .223 Wylde Premium Series Barrel - $220
Sharps XPB Bolt Carrier Group - $189
Law Tactical Folding Adapter - $229
SB Tactical Brace - $120
CMC Trigger - $195
Sig Sauer Whiskey5 1-5x20 optic - $550 
Aero Precision 30mm Scope Mount - $99
Sneaky Bags 27” SPYDER Bag - $180
KNS Precision Anti Rotation pins $30
Misc Parts - $80
Silver Grey Cerakote $300
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Total $2,741
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SOURCES
Shop the complete selection at Brownells.com 

Primary Weapon Systems - https://primaryweapons.com
Ballistic Advantage - https://ballisticadvantage.com/

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