Someone in the "Why all the AR hate" thread said "because they are ignorant of the advantages of the direct gas system"


I decided to start a seperate thread on that.


My question is, what are the advantages of a direct gas system????


When I hear bashing of the AR, the one thing that stands out, the overwhelmingly hated thing, the most common attack or bash of the AR is its gas system. I know this probably has been discussed 1,000 times here, but I am a newbie and have been searching and haven't found much info.

When told how sh*tty the gas system is, or that the AR "sh*ts where it eats"...what do I respond with? What do I say to explain to someone exactly why the direct gas system is better or at least equal?


I have heard that it is more accurate, and more reliable because of less parts (no piston, or op-rod). But is it just that? Is it that simple? Did stoner design this system just because it is more accurate? I just don't see how or why there should have been a massive change in the fundamental operation of a gas system simply for accuracy, especially when piston systems are pretty accurate. I don't want to speculate, since I don't know what was going through Stoner's mind, but I assume there there had to be MANY reasons why the direct gas system was invented and implemented - not just 1 or 2 reasons that barely justify it....

"When told how sh*tty the gas system is, or that the AR "sh*ts where it eats"...what do I respond with? What do I say to explain to someone exactly why the direct gas system is better or at least equal?


I have heard that it is more accurate, and more reliable because of less parts (no piston, or op-rod). But is it just that? Is it that simple? Did stoner design this system just because it is more accurate? I just don't see how or why there should have been a massive change in the fundamental operation of a gas system simply for accuracy, especially when piston systems are pretty accurate. I don't want to speculate, since I don't know what was going through Stoner's mind, but I assume there there had to be MANY reasons why the direct gas system was invented and implemented - not just 1 or 2 reasons that barely justify it...."

Hk's "shit where they eat",  yet people don't cry about their reliability.   Lighter, cheaper, more accurate for less money.  You don't see anyone talking about unitized gas cylinders or glass bedding for AR' s now do you?

Well....that still doesn't quite explain the overall philosophy behind the AR gas system. Mentioning the HK fluted chamber does point out a double standard....but that isn't a good talking point for why the AR system is better.


Accurcy I can see. Cheaper...ya. But cheap isn't always "better" on the battlefield. It isn't a feature for use, it is a feature for government cheap asses.



Does the AR system allow tighter lock up? Does it offer more reliable cycling? It is less sensitive to varying pressure? Less maintenance? Gotta be some serious thought behind it beyond accuracy...

Don't know if this will help, but...there was some good info here....www.ar15.com/forums/topic.html?b=3&f=118&t=199117


As far as I can tell, the advantages are:

1. Lighter weight
2. Less complexity, less moving parts.

I also think that Stoner felt, in the back of his mind, that to go with the
"radical" (at the time) aluminuim upper and lower he'd need to go with
a system that worked/locked up different than any other system....which
MIGHT have influenced his thinking.....

AoD

One advantage I have seen mentioned is that any crap that gets into the action gets blown out by the gasses being blown into the action/chamber out through the ejection port.  A piston driven design doesn't do that.

I'm not Gene Stoner, but I seriously doubt that accuracy was the reason why he put in the direct gas system.  My bet is, again, weight.  One major purpose of several ArmaLITE rifles was to reduce the weight.  That's why the original AR15/M16A1 had components made of plastic and aluminum.  This was a major innovation in the day, and the direct gas system allows you to shave some more weight - to the point that the original AR-15 was somewhere around 6 lbs., as I recall.  

As for accuracy, there's much speculation as to why the AR-system rifles are so accurate, but as far as I can see not proof.   Some say the upper/lower system, some say it's the bolt (I would definintely say that the QC standards of the bolt have something to do with it), some say the gas system which minimizes pressures on the barrel.    

Tell you what, take 60 high quality barrels (say, Douglass premium air gauged), put 30 on a normal AR-15 and another 30 on a proven gas-piston AR.   Shoot 10 10-round groups at 300yd. in a wind tunnel on 2-3 nonconsecutive days.  Then, tell me if the piston uppers are/aren't more demonstrably more accurate than the gas-impingement uppers.  

Short of that, AFAIC, the jury is still out.  

Interesting,

If it was purely based on saving weight, what does that say about this system today given how FAR its come since the original AR-15? Now the rifle is much heavier. Makes the weight savings of the gas system moot. Especially by those with heavy barrels and many mods and rails - why skimp on ounces for a piston/op-rod when you blow 3-4lbs on other things? I suppose you can argue that every ounce counts, but in in respect to the original design concept (assuming weight saving was a major concern), I can't see that as a positive.


Has anyone made the argument that it is more reliable? I read on another thread (linked above) that the AR gains a form of reliability feature by "blowing out" debris.


You can argue that the system is more simple - has less parts. It is basically just a tube. Does it really have less gas system parts if you include the gas system related parts on the bolt & carrier?


One thing I seem to guess from reading here is that breakage is a serious advantage. I don't know how much piston systems break, but what is to break on a gas tube that leads into a gas key then to a bolt that has gas rings? Not much I would say....