Piston ARs

[pnarq5]

I saw this Patriot Ordnance Factory (P-308,AR-10 like) in the Book of the AR-15. I went to their website and see they make piston AR-15s too. I like what I see but wanted to get some expert opinions. Can you get the best of both worlds(AR/AK)?
The P-308 shot .75 MOA@100yards!

http://www.pof-usa.com/POF-USA%20NEWS.htm

[dport]

I'm surprised this hasn't gone into a rant about how there is nothing wrong with DI guns.

I have a POF and I have Bushmaster. I like both.

The advantages of the piston gun:
Doesn't need as much lube.
Is more tolerant of not being cleaned.
Is generally more reliable in short barreled weapons.
Keeps the bolt cool. Only really an issue if you're in a habit of going through 10s of thousands of rounds.

Advantages of the DI gun.
Can be lighter than it's piston counterpart.
Is usually more accurate than it's piston counterpart.
Is plenty reliable with proper cleaining and lubrication


I'm sure there are others, but that's a start.

[pnarq5]

Thanks for the insight.

Any pics would be great too!

[Daynja]

I wish the piston system was more widely accepted for the AR15. Old habits die hard and people can not get over the AR15's gas system. If I hear something like "not milspec" again I'm going to barf.

The biggest things to consider about a piston system is that it doesn't get as dirty and is much easier to clean, but is probably a little less accurate.

The correct answer is to get both. :)

[RMTactical]

I guess if it were as big a problem as some claim (most don't shoot AR's), there'd probably be a good reason to change it up.

It's hard for me to want a heavier, more expensive upper with just more stuff that can break when my AR's are working just fine as is.

[neeko]

Yeah if they werent so damn expensive I'd consider one.

[pnarq5]

Is it less accurate because of there are heavy parts moving before the round leaves the barrel?
Does the bolt move in either before round is out of the barrel?

[dport]

Originally posted by pnarq5
Is it less accurate because of there are heavy parts moving before the round leaves the barrel?
Does the bolt move in either before round is out of the barrel? One theory says it's the reciprocating mass. Another theory has to do with the free floating of the barrel. Leitner-Wise has built some pretty accurate piston guns. As accurate as a DI gun? Who knows at this point?


Someone brought up more parts. And that is true. There are two more parts to my POF than my Bushy. It's a pretty straight forward set up, and I don't see it as being more that can go wrong in reality. The POF uses a similar gas system to the FAL, and as far as I can tell it uses fewer parts than an FAL. The FAL has proven to be pretty bullet proof over the last 50 years.

[spober]

Originally posted by GoreLicks
I guess if it were as big a problem as some claim (most don't shoot AR's), there'd probably be a good reason to change it up.

It's hard for me to want a heavier, more expensive upper with just more stuff that can break when my AR's are working just fine as is. ill second that.:soap:

[gunman_23]

If those piston uppers were more affordable Id be more than happy to trade in long range accuracy.
I imagine that if the technology takes off in a few years one should be able to grab one for $500-$600.


Just my .02

[TimP]

they are no more $$$ than a quality upper.

[jonathon]

The reliability "problems" everyone complains about comes from the tighter tolerances and how the bolt locks up.. not the gas system.

Though, they are plenty reliable when kept even somewhat cleaned and lubed. Most arn't even too picky about that.

[22highcaps]

The POF may add a few parts compared to a DI, but it loses a few parts compared to DI too. The parts it adds are less likely to fail than the 3 gas rings on the bolt it loses. The POF may shift the balance forward compared to a Govt or Pencil profiled DI AR, but it is certainly no worse than an unfluted bull barreled AR with an aluminum handguard. Given the current stainless "recon" barrel fad combined with ever longer quad rails (13.2" of larue for instance), I do not see the added mass is out of line with today's market.

[Titurel]

Along with tighter mechanical tolerances, the AR15 derives some of its accuracy potential from a design where all the movement in the firing cycle occurs in a straight line. The barrel, bolt, carrier and receiver extension tube are co-axially aligned. Introducing a piston disrupts this balance. The piston begins to move before the bullet has left the barrel and creates an inertia which will tend to pull the rifle off target. Obviously there are some very accurate gas piston rifles, but none of the most highly accurate semi auto rifles use a piston (ie., H&K PSG1, AR15, SR25, M82A1)

As far as reliability, one solution our military is considering is an electronic round counter. Maintenance needs to be performed based on how many rounds have been fired, not simply a scheduled time period. One soldier's M4 might blaze through more ammo in a week than another's would in six months. If an armorer could tell exactly how many rounds had been fired by a given rifle, proper maintenance could be performed and many problems avoided.

[22highcaps]

Originally posted by Titurel
Obviously there are some very accurate gas piston rifles, but none of the most highly accurate semi auto rifles use a piston (ie., H&K PSG1, AR15, SR25, M82A1)



M82A1 ain't exactly the most accurate gun out there. Also, what about the M1A?

[TruffleShuffle]

Originally posted by GoreLicks
I guess if it were as big a problem as some claim (most don't shoot AR's), there'd probably be a good reason to change it up.

It's hard for me to want a heavier, more expensive upper with just more stuff that can break when my AR's are working just fine as is.

Absolutely,

This is a fix to a non-existant problem...... you clean your stuff, or you buy mil-spec parts.... and there are no issues with these guns! Why would I pay hundreds of dollars for extra parts, that don't do anything?

[crazymoose]

Originally posted by GoreLicks
I guess if it were as big a problem as some claim (most don't shoot AR's), there'd probably be a good reason to change it up.

It's hard for me to want a heavier, more expensive upper with just more stuff that can break when my AR's are working just fine as is.

I'm a fan of the piston uppers. First, anything that decreases the amount of fouling in an AR is pretty welcome to me.

Second, it's not so much that the piston uppers have "more stuff" so much as different stuff. Sure, there's a FAL-ish piston setup, but you also no longer have the gas key/rings to worry about, which are a common source of problems. The real benefit, however, is for military users. The manufacturers themselves say the prime benefit of the piston arrangement is reduced heat buildup in the receiver. Ever wonder why ARs frequently snap lugs on the bolt during sustained auto fire? Perhaps it has something to do with hot propellant gasses being blown onto the bolt/carrier. I'll admit the piston offers nothing except easier maintenance to us civilians, but for someone who might burn through a bunch of mags quickly in a firefight, I can see the piston offering better reliability and parts durability.

[switch625]

Originally posted by neeko
Yeah if they werent so damn expensive I'd consider one. Me too.

[Alaskapopo]

Originally posted by GoreLicks
I guess if it were as big a problem as some claim (most don't shoot AR's), there'd probably be a good reason to change it up.

It's hard for me to want a heavier, more expensive upper with just more stuff that can break when my AR's are working just fine as is.

I think its a good idea especially for short barrled guns. I have yet to see a 10 inch gun make it through a training class without going down. I love AR15's but the HK416 sounds really good to me. An AR15 thats less maintance intensive can only be a good thing.
Pat