Copyright © & TM 2012 ~ POF-USA Patriot Ordnance Factory, Inc.  All Rights Reserved.

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The Gas Piston System

So, what’s the big deal?  Another AR-15 just like all the rest, right?  My thoughts exactly, back in 2005, when I first saw the P415.  I was (and still am) a little jaded when it comes to AR-15 variants.  Except for a few cosmetic changes, they all look and operate the same as the M-16’s and M-4’s that I have been using for almost 30 years.  Some are better than others, a few have better-than-Mil-spec parts, but none are innovative or represent any significant improvement.  That all changed with the POF Regulated Gas Piston System.


   In 2002, Frank DeSomma, an aerospace engineer with no background in weapon design, saw the two most serious problems that plagued the AR-15; carbon fouling and the short-barreled timing issue.  But, unlike the rest of us, he was not willing to just “deal with it.”  He thought he could fix it.  And that’s exactly what he did.

   The POF-USA Regulated Short-Stroke Gas Piston System is easy to understand. Rather than operating gas being injected directly into the upper receiver, it simply pushes a piston that acts on an operating rod (op-rod).  The op-rod then acts on the bolt carrier, setting extraction and reloading into motion.  This action type offers several significant improvements over the direct impingement method.  First, POF guns run very clean because hot gases are not injected into the upper receiver.  Carbon fouling in the action is virtually eliminated.  Incidentally, the gun runs much cooler; further enhancing reliability and safety.  Secondly (and arguably more importantly) POF has solved the timing problems that plague all AR-15’s with short gas tubes.  Through precise op-rod/piston geometry and regulated gas pressure, all POF rifles and carbines are properly timed and bolt speeds (cyclic rates) are precisely controlled.  This greatly enhances extraction and feeding reliability, as well as reduces wear and fatigue on critical components.

See the POF Gas Piston System in action.

   Additionally, POF has since led the industry in high-performance metal finishes and coatings.  Taking cues from Frank’s aerospace background, POF rifles feature state of the art NP3™ coatings and extremely hard, corrosion resistant, nitride heat-treated barrels and gas blocks.  Together, they allow POF to boldly state that these weapons require no lubrication to function properly and reliably.  No oil in the action is a very big deal to soldiers and other war-fighters operating in the desert theaters.


   The intent of this article is to help answer the question: “So, what’s the big deal?” As simple as it may appear here, it took serious innovation to get a gas piston system to work reliably in the AR-15 platform.  The integral bolt-carrier key (with the interface behind the cam pin), oversized heat-sink barrel nut, roller cam pin, and regulating gas plug are just a few examples of innovations that came from Patriot Ordnance Factory.  When Frank first introduced his gas piston variant AR-15, industry leaders laughed at the idea.  Today, every major manufacturer is following POF’s lead with their own gas piston rifles.  That says a lot for a company that was started in the owner’s garage only 10 years ago.


U.S. ARMY Special Forces (RET)

The Gas Impingement System

The Stoner Direct Gas Impingement AR-15 (in one variation or another) has been in continuous service with the US military for over 40 years.  This is a long time and a testament to the design; however, it’s not without its faults.


   When a round is fired, a portion of the gas produced by the burning gunpowder is vented into the gas block, (usually integrated in the base of the front sight).  Here the gas does a 180-degree turn down the gas tube, back into the upper receiver, through the gas key, and is finally injected directly into the bolt carrier group under sufficient pressure to operate the action.  There are a series of problems associated with this design: carbon fouling, continuous lubrication, and timing issues with short-barreled variants.


   When the M-16 was first issued to soldiers, they immediately reported reliability problems.  Unlike the AK-47, the M-16 is built with tight tolerances for solid accuracy.  Consequently, it cannot tolerate a lot of dirt and fouling in the action.  Perhaps contrary to its reputation, the AR-15 is well protected from external contaminants.  The weapon’s non-reciprocating charging handle, ejection port dust cover, and tight fitting magazine all work to keep debris out of the mechanism.  The weapon’s fouling problems are not from outside elements, but from its own “internal combustion”. The best way we dealt with this problem was frequent cleaning and plenty of lubrication.  At least this was true until we started operating in the extreme sand and dust environments.  Most who operate in the desert will tell you to run your gun fairly dry.  That, or risk the fine dust sticking to the oil and gumming it up.


   Furthermore, short-barreled gas impingement AR’s like the M-4 carbine have a gas tube shorter than the system was designed to operate with.  Eugene Stoner designed the M-16 to have a 20” barrel.  That length utilizes a specific gas block position and gas tube length to properly time the action.  Shorter gas tubes result in an over-pressured weapon with critically high bolt speeds prone to extraction (1) and feeding malfunctions (3); not to mention broken extractors, blown primers, and case-rim failures.  But instead of fixing the timing, the industry addressed these issues with brute force.  Heavy buffers and buffer springs, extra heavy-duty extractor springs (complete with rubber o-rings), and “high reliability” magazines were all invented to help force extraction (2) and get the next round to feed.  But not one of these “fixes” was addressing the short-barreled rifle’s real problem: proper gas regulation.  Enter Patriot Ordnance Factory.

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american owned • american made

Copyright © & TM 2012 ~ POF-USA Patriot Ordnance Factory, Inc.  All Rights Reserved.