Saturday, April 2, 2016

Superlative Arms Short Stroke Retrofit AR15 Piston System Review

Superlative Arms Short Stroke Retrofit AR15 Piston System Review

Over the last decade, piston driven AR systems have gained a lot of attention due to their ability to deliver cooler running reliability similar to the exceedingly reliable piston based AK platform. One of the many advantages of the AK platform has been its piston based operation which isolates operation gas pressures at the front to the gun away from the shooter and bolt and trigger group. This piston based system delivers a cooler and clearer running AK gun which arguably delivers more reliability. Some very bright folks figured out several way to transfer that piston system over the the AR15 platform thus combining the accuracy of the AR15 platform with the reliability of the AK.  

There have been a number of companies offering short and long stroke piston systems including Adams Arms, H&K, LWRC, Sig, Syrac, PWS and even Ruger. Long Stroke systems have the op rod attached to the bolt carrier such as AK’s and Tavor’s. Op rods are not attached to the bolt carrier on short stroke systems. The main compromise between the two is that the Long Stroke system’s design are typically heavier but inherently offer an integrated gas design that bleeds off excessive gases. The new Superlative Arms patented system extends this bleed off capability to a low profile Short Stroke system all while still providing gas pressure adjustment.

Let me first point out that Superlative Arms is the co-patent holder of the design offered by Syrac Ordnance and was also its manufacturing partner of the Syrac adjustable gas block and Piston system product line. Superlative could have been offering its own line of adjustable gas blocks and piston systems identical to Syrac’s however they developed their own unique patented gas bleed off design. Superlative’s bleed-off system is offered in both a direct impingement adjustable gas block and also in the co-patented short stroke low profile gas system. Though there are many similarities, Superlative Arms is now aggressively going to market with their own systems.

Both of Superlative Arms DI or Piston systems use their patented Bleed-Off gas system.  Instead of limiting the gas pressure, the bleed-off system functions more like a pressure regulator which limits the gas delivered to the gas tube or op rod piston and the rest of the excess gas is vented out the front of the gas block. Typical adjustable gas block systems have had some problems due to gas port and adjustment screw erosion from the captive excessive gas temperatures and pressures at the gas port. Many of us have seen this problem manifest themselves in wandering gas settings or even adjustment screw blowouts.

By porting and venting off that excessive high heat pressure the instant the pressure hits the gas block, the Superlative Arms system greatly reduces erosion and pressure based failure problems right at the gas block all while running cooler and cleaner for both their DI and piston systems. This bleed-off design in turn reduced the beating delivered to the adjustment mechanism and op rod.

Some previous short stroke piston systems have experienced problems with gas block durability and retempering of the op rod springs. In order to assure completely problem-free operation Superlative goes the extra mile and makes the piston block from melonited 416 stainless steel and uses a heat treated Inconel steel spring which is impervious to the pressures and heat generated by an AR15 even running in full auto.  Superlative has accomplished this design feat all within a very small compact low profile design that is barely larger than most low profile gas block designs.

Superlative Arms DI adjustable bleed-off gas block is a simple swap for people who want to retain a DI based system. Pull off the old gas block, move the gas tube to the new Superlative gas block, reinstall, tune to assure reliable last round lock back and you done. Like all retrofit gas piston systems, the Superlative arms kit install is a bit more involved.

The Superlative Arms retrofit gas piston system includes everything a user would need for conversion of a existing AR15 including the gas block, op rod, op rod spring, and carrier. Any AR15 bolt of your choice can be used with their carrier. All the Superlative kits are all essentially the same with the exception of the pistol, carbine, mid, and rifle op rod lengths - just order the appropriate gas rod length specific kit. If you did decide to move a carbine to a rifle length rifle, all you would need would be a replacement rifle length op rod.

First time installation requires some patience and about thirty minutes. After learning the install process on my first build, I completed the pistol build conversion in about fifteen minutes.  Unlike a DI gas block install, the left/right and fore/aft alignment of the gas block is critical to reliable operation. With a stiff fixed op rod responsible for converting the blast of air inside the gas block to a shove on the carrier, it has to be free from any binding and also precisely the right length from the face of the carrier to the gas block.

The basic process is to install the gas block loosely on the barrel and insert the stripped op rod (minus the spring) into the gas block and tighten down the gas block piston plug. Then the task is to assure the op rod spins freely without binding with the carrier (minus bolt) fully seated in the upper receiver. If you have a fully seated carrier and freely spinning op rod then you can tighten down the gas block. If the carrier does not fully seat or the op rod does not spin freely, the gas block needs to be turned or moved out as appropriate. Of note the gas block should not be slammed right against the shoulder on the barrel - my installed both required positioning the gas block off the shoulder of the barrel about 1/32”.

Once those initial adjustments are made, the op rod is removed and then re-installed with the spring and the plug fully seated then backed out on-half turn.  Similarly the carrier is removed and reinstalled complete with a bolt, cam pin, firing pin, and retaining pin. A final installation check is made to assure the carrier fully seats and positive hammer drop is achieved.  All that is required now is to adjust the gas pressure in a process similar to any adjustable gas block.

This is a rise and repeat process of assuring the gas block sees just a bit more pressure than is required to offer a last round hold back of the carrier - generally one half turn pressure increase tuning over the lowest setting that will hold the bolt back.  The entire retrofit process is not particularly difficult, however you just cannot be as sloppy on the install as you would with a DI based gas system. All piston systems demand perfect alignment but once aligned it should be a set it and forget it deal.

Technically the Superlative Arms Retrofit Low Profile Piston system can be used with any AR15 rifle or pistol build, however I always have to do something a big unique. In this case I opted for a custom rebuild of my Yankee Hill Machine rifle with a raw hand polished un-anodized billet Joe Bob Outfitters Spartan upper and lower receiver set, newly released CMC 2-Stage trigger, Ace Skeleton stock, Nikon 2-7 P223 Optic, and Faxxon Hex rail.  The original re-used barrel is a 20” diamond fluted and heavy fluted YHM barrel featured a 1:9 twist rifle length gas system. As re-used was the YHM bolt on the Superlative Arms carrier. This build really was a test of the systems low pressure operation. Rifle length gas systems typically push the coolest, lowest, and softest pressure into the gas system when compared to higher pressure mid, carbine, and pistol length systems.

The second build was a conversion of a previous Aero Precision and Phase 5 Tactical  AR15 pistol build. AR15 pistols gas pressure are notoriously high with some manufacturers offering compensating options such as heavier buffers and buffer springs. A standard buffer spring was swapped for the heavier rate Phase 5 spring to see if the pressure could be reduced to take a little snap out of this AR15 pistol’s recoil. This was a test of how the Superlative Piston system would handle high pressure systems and it worked flawlessly.

If you are familiar with Syrac’s top notch gas block quality then you are already familiar with Superlative’s Manufacturing quality since they have been the manufacturer up to this point. The fit and finish is outstanding and the Ion Bond finish on the carrier and melonite on the block finishes are excellent.

Functionally the system offers a lot of advantages including being able to tune the pressure to just enough to drive the bolt carrier. The result is that there is less recoil, cooler running system, less carbon build up, and greatly reduced gas blowback on SBRs and AR15 pistols.

I really did not showcase the Superlative Direct Impingement adjustable gas block, however it works similar to all the other systems on the market but with more refinement. Superlative’s gas block is not just a screw tapped into the gas block, the gas bleed off design is something a bit different which offers many potential advantages. Only a 1000 or so rounds in, I am impressed with both their DI and Piston retrofit kit solutions. Both offer something that is different than anything on the market, and a design which potentially offer greatly expanded durability over traditional AR15 piston systems. I have commented many times that an adjustable gas system is the best upgrade any AR owner can make - note due to the low pressure issues I do not recommend any adjustable gas system for 300 Blackout or 7.62x39 AR15 builds. Superlative is one of the adjustable gas blocks systems which has moved to the top of my list if you want the best solution available.

Firearm Type:  AR15
Gas Length:  Pistol
Barrel Diameter:  0.750"
Weight:  12.8 oz.
Piston Block Attachment Type:  Solid, Set Screw
Piston Block Material and Finish:  416 SS, Melonite
Carrier:  Ion Bonded, 1 pc. Carrier w/ Skis and Dimpled Key
Gas Adjustment:  (Patent Pending) 30 Locked Positions, Front Of Block
Bleed Off Port:  (Patent Pending) Front Of Block
Piston Block Assembly
Carrier (bolt not included).
(1) 3/32" X 6"  Hex Key  (tool to adjust gas screw)
(1) 9/64" X 6" Hex key  (tool to install/remove gas block plug)
(1) Bushing and insert tool (Just an extra.... we have had some requests.  Use at your discretion).
Installation Instructions & QR Code For Video Tutorial
MSRP $289


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Unknown said...

Thank you Major P.for blogging this company's new products.

I have been following Syrac's new piston kit...but this new kit from Superlative Arms put an even greater amount of tech into the finished product.
I am glad I waited. I plan on getting a SA kit as soon as I can. Why are there not any comments on this incredible new ultra light, unique piston kit? Not a single video on You Tube yet either.
There seems to be plenty positive post by users on

I keep telling everyone the same thing: "Get an adjustable gas system where it is DI OR piston driven". It should be your first mod before any thing else!!!

Unknown said...

Superlative arms has a great video on the whole setup and more, very good stuff, I can't wait to get mine

Unknown said...

Superlative arms has a great video on the whole setup and more, very good stuff, I can't wait to get mine

Unknown said...

Why the non-recommend of adjustable blocks/piston kits for 300BLK and 7.62x39? Wouldn't the adjustable nature of this piston kit and of adjustable blocks allow you to more precisely manage the operation of the bolt carrier as the weapon cycles (aka more gas for a failure to lock open, less for a suppressed system)?

Unknown said...

Why the non-recommend for adjustable DI/piston kits on 300BLK and 7.62x39 ARs? Wouldn't the adjustable nature of these systems allow the operator to more precisely control the amount of gas used in the system, permitting one to correct for an under or over-gassed situation?

Major Pandemic said...

300 Blackout and 7.62x39 barely have enough pressure to operate normally. In the AR format the low pressures the produce really negate the need for an adjustable gas system. Usually you need to do things to increase pressure to assure proper operations.

Unknown said...

What about running a suppressor? Wouldn't that warrant the need for adj. gas??

Major Pandemic said...

I would depend on the suppressor. Some have a lot of back pressure that needs to be managed. Others you can probably do away with a bunch of post suppressor tuning.