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Evolution of AR Design

Oddball Six

Commander of Meh
Minuteman
Apr 2, 2010
540
47
40°25′N, 104°43′W
Does anyone have a good link to a thorough, detailed discussion of the view that some seem to hold that "if you want a gas piston gun, you should choose one built from the ground up for piston, not an AR"?

Recently there have been a number of posts here where people hold that view. Even George @ GAP seems to have the perspective that for the AR platform, staying with a DI action seems to be the "right" choice for functionality and dependability.

Still, basic googling reveals lots of forum comments in different places, some apparently more trustworthy, some less so. Hard detail and an exploration of the platform functional differences is much more challenging to find.

I am hoping that someone can save me some time. The car is an evolution over time on the same basic principle. A powerplant turns a shaft of some kind connected to gears which turn wheels. Along its path of evolution, we have seen a number of points where the way that the powerplant, the shaft, the gears, etc all work has changed radically. We have similarly seen points where the design was kept and simply made more efficient.

I expect that this is a similar issue and I would like to understand both sides - the AR piston gun as simple evolution when properly engineered AND the case for choosing a different platform entirely if one wants a piston driven action cycle.

Anyone have some good links?
 
Re: Evolution of AR Design

As far as I have seen, all the debates and forums are heavily filled with personal opinions. As for your reference to the evolution of the automobile, we all still rely heavily on the internal combustion engine. Some have tried to engineer hybrid and electric engines but thy are all crap. Oops, there's my opinion again.
 
Re: Evolution of AR Design

I have tried several piston systems including the ACR and SCAR, even a Sig and am back to running a DI operated rig. I tested them all and picked the SCAR as my go-to but while running through a course several times one day a buddy commented that I was faster and more accurate with my DI mid gas rifle than the SCAR. Clocked I am 47 seconds faster through the course. I have not run the HK 417. Some of the piston rifles were opening the bolt while the bullet was still in the bore, flames shooting out of the ejection port and accuracy was terrible. Reports say the SCAR is knocking out the optics after hard use in the sand box.
 
Re: Evolution of AR Design

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: bustin</div><div class="ubbcode-body">I have tried several piston systems including the ACR and SCAR, even a Sig and am back to running a DI operated rig. I tested them all and picked the SCAR as my go-to but while running through a course several times one day a buddy commented that I was faster and more accurate with my DI mid gas rifle than the SCAR.

Clocked I am 47 seconds faster through the course. I have not run the HK 417. Some of the piston rifles were opening the bolt while the bullet was still in the bore, flames shooting out of the ejection port and accuracy was terrible. Reports say the SCAR is knocking out the optics after hard use in the sand box.</div></div>

I guess the challenge that I have, and really where I am going with this is that there are a lot of intelligent people with solid experience they have been kind enough to share which indicates that the gas update to the AR can be done wrong.

<span style="font-weight: bold"><span style="font-style: italic">BUT</span>..Can it be done <span style="font-weight: bold">right</span>?</span> Can it be just an evolution of the present design OR <span style="font-style: italic">must</span> it always result in weakening of the system and thus should be a from-the-bottom-up kind of change?
 
Re: Evolution of AR Design

Recent news reports the USMC intends replacing the M-249 SAW with the H&K IAR, and is fielding it in combat in something that amounts to Beta testing. I'm thinking that's a mighty demanding application for a gas piston operating system. Obviously, the final results are not yet in; but The Corps selected the IAR after testing four competing systems. This might qualify as definitive testing, IMHO, and the key problem to follow for guys like us is to get one in a semiauto version, with a legal barrel length. Personally, I could also make do with some more sporting-like furniture. Versions like the H&K MR556A1 and MR762A1 engender my interest greatly. Very pricey, but still interesting.

Greg
 
Re: Evolution of AR Design

The USMC has cleared the IAR to be a go permanently and placed their order. The M4 variant they are using is the first AR platform tested by HP white to have zero failures in their 6000 round test. There's a pretty objective opinion-less test about the latest phase in the platform's evolution. I have a POF and have similar experiences in shooting it, and my next build will be a B.E.A.R. Elite.

"Tested by H.P. White Laboratory, a known leader in small arms and ammunition research and testing, the B.E.A.R.™ was found to have no failures or stoppages in a 6000 round endurance test and delivered a high degree of accuracy using Federal Match (69-grain) ammunition in the dispersion testing (.88” at 100 yards). Additionally, no malfunctions occurred during adverse environment testing, including immersion in water and sand."

That's from Sniper's Hide front page article announcing the B.E.A.R. elite. It's an evolution of the piston system.

Edit: the way I worded the first paragraph makes it sound like the B.E.A.R. Elite is the Marine rifle, that's not the case it's just the same type of piston AR. The marines are using an HK built piston AR as stated previously. Sorry for any confusion.
 
Re: Evolution of AR Design

After testing the rest the HK is the ONLY system I would want to test. The Sig is smooth but heavy(an AK type system). The SCAR runs and runs but doesn't point like an AR and may beat the optics apart. Most other systems have all kinds of problems that make them more of a liability. IMO a ground up design is the only way to make a piston work right. If it is a ground up is it really evolution? It could be done but no one has done it yet.
 
Re: Evolution of AR Design

To the OP - here's a great article on the evolution of the AR in Military terms. Now they are switching to adding piston systems to compensate for the problems DI has with shorter barrel lengths. DEVGRU has been using this for quite some time, now widely popularized with Bin Laden's death at the business end of a 416.

http://www.ar15.com/content/articles/history/evolution.html

Marcus, I'm ignorant to any history of a piston AR preceding the DI system, are you referring to other types of rifles using pistons or can you shed some light on the subject for me?