Addax Tactical Gas Piston AR-15 Upper

Addax Tactical AR-15 gas piston uppers.
Addax Tactical AR-15 gas piston uppers.

There has been much talk about improving the AR-15/M-16 with a gas piston system rather than the direct gas impingement system in use since the 60’s.  Companies like the Ruger have attempted to capitalize on this trend by producing gas piston rifles such as the SR556.  If you already own an AR or two, you can retrofit your gun with a piston system, potentially saving you hundreds of dollars.

Addax Tactical makes a gas piston upper for the AR-platform called the ATAC-GPU or Advanced Tactical AR Carbine Gas Piston Upper.  Addax Tactical states the ATAC-GPU “utilizes a specially designed, self regulating, long stroke piston system for enhanced dwell time and lower recoil.”

The ATAC-GPU is manufactured with mil-spec and match-grade parts, and Addax Tactical says it is built tough enough for all law enforcement and military applications.

Available options for the ATAC-GPU include Vltor MUR upper receivers, cold hammer forged 16″ barrels, 10.5″ – 16″ mil-spec barrels, compensators, flash suppressors, and a variety of Cerrakote finishes.  Addax offer the uppers in 5.56 (aka .223) and 6.5 Grendel and 6.8 SPC.  Prices start at $875 and go up depending on what options you want.


Update:  This specific system is not currently available from Addax Tactical.  Other AR-15 piston uppers are available from Addax and other companies.  A quick Google search can help you find a system that will work for you.  I do not know if this system will be coming available in the future, or if this is a dead product now.  If someone has any insight into this piston upper situation, please add to the discussion in the comments section below.  I know I would like to know more information, and I’m sure other readers would like to hear about it as well.  Also, if there is anyone who is running one of these uppers now, let us know how you like it.

By Richard Johnson

Richard Johnson is a gun writer, amateur historian and - most importantly - a dad. He's done a lot of silly things in his life, but quitting police work to follow his passion of writing about guns was one of the smartest things he ever did. He founded this site and continues to manage its operation.

6 replies on “Addax Tactical Gas Piston AR-15 Upper”

For that price you can buy a whole new rifle. Upper and lower. These prices are out of control. I dont understand how you can buy a base S&W M&P15 Flat Top AR for $900 and a M&P 45c pistol for $250 less @ $650. Either the pistols are overpriced or they all are. Let the fleecing of America continue with exploitation of our 2nd ammendment. Adam Arms offers a piston system for $500 which isnt cheap by any means, but if you have to have a piston system and you want to save money theres $175 in your pocket by buying it. Capitalism ROCKS! Bend over America!

I’ve heard these type of retro-fits can cause the bolt assembly to wear on the inside of the upper receiver at a funny angle due to the way in which the rod “unnaturally” pushes the bolt assy. backwards. Is this the case with this modification?

I heard the same thing. The rear of the bolt gets shoved down and to gouges the lower reciever. I think that is with ANY Retofit piston system. Not sure if is the case with the ruget SR-556.

Long-strok?! Isnt long-stroke the AK way or Im missing something? Cause the AK mechanism is known for downgrading accuracy…

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