Adams Arms Retrofit Gas Piston System (RGPS) for Tactical AR-15 Carbines

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By David Crane
defrev at gmail dot com

September 19, 2008
Adams Arms, Inc. is offering an "AR15 Fix" a.k.a. "Retrofit Gas Piston System (RGPS)" (Patent Pending) that will all you to easily convert your direct-gas-impingement (DGI) tactical AR carbine (tactical AR-15 carbine) into a short-stroke gas piston/op-rod system in about ten (10) minutes. The RGPS, described by the company as a "Retrofit Piston-Driven Cycling System", is a drop-in gas piston/op-rod kit that replaces the standard gas block, gas tube and gas key, and is compatible with the A.R.M.S. S.I.R. system.


Claimed advantages of the system are the following:…

– Faster target acquisition
– Completely eliminates hot gases from entering the receiver
– Lowers recoil 30 to 40 percent by using a short stroke shaft
– Improves accuracy by lowering recoil
– Makes the weapon more reliable over a longer term of use
– Easy access from front of block with out removing hand guard

DefenseReview has heard and read some good things about the Adams Arms drop-in gas piston/op-rod system for tactical ARs (tactical AR-15 carbines), but we haven’t run it, yet. However, Small Arms Review (SAR) has, and they’ve published an article on it by Chris Choat. Choat ran 500+ rounds of various 5.56mm ammo types through the retrofitted carbine unsuppressed, and 100+ more rounds were fired through it with a muzzle can (silencer/sound suppressor) attached. At the start of the test, while firing the weapon unsuppressed, the fourth and sixth round fired and ejected by the gun failed to pick up and feed the next round from the magazine. The working theory for this is that the drive rod spring wasn’t fully seated against the delta ring/barrel nut. This happened while using XM855 ball ammo, specifically 5.56x45mm NATO (5.56mm NATO)/.223 Rem. ammo. After the second malfunction (on the 6th round), there were no further malfunctions of any kind, including during suppressed fire.

It should be noted that during SAR’s testing, the Adams Arms retrofit-outfitted carbine was run completely dry with no lubricant whatsoever. The article describes the complete installation procedure. This article is definitely worth reading, and can be downloaded in PDF format by clicking on this link. Beware: It may take awhile to download.

Samson Manufacturing may already be manufacturing optional rail systems specifically for the RGPS. If they are, it would seem logical that these rail systems would be variants of the Samson Tactical Accessory Rails System a.k.a. S.T.A.R. System. We’ll look into it.

Company Contact Info:

Adams Arms, Inc.
Dept. DR
255 Hedden Ct.
Palm harbor, FL 34683
727-853-0550 Office
727-853-0551 Fax Email

Additional Photos:

Photo Credits: Adams Arms

Adams Arms Retrofit Gas Piston System (RGPS) for Tactical AR-15 Carbines by

About David Crane

David Crane started publishing online in 2001. Since that time, governments, military organizations, Special Operators (i.e. professional trigger pullers), agencies, and civilian tactical shooters the world over have come to depend on Defense Review as the authoritative source of news and information on "the latest and greatest" in the field of military defense and tactical technology and hardware, including tactical firearms, ammunition, equipment, gear, and training.

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