A friend want's to get an ar and as being a lefty I turned him on to a stag. For now they only can get a piston(8L) model. I don't really know enought about piston driven ar's to give him a honest opinion on pro or con's. Any advice would be most helpful befor he puts his $2000.00 down.Thx
piston vrs gas ar
- Thread starter cormann2
- Start date
The AR platform was designed with direct impingment in mind and is optimized for that operating mechanism.
Adding a piston is something I don;t see the point of, personally. There are a LOT of other rifles out there that are purpose-build for piston and do it better:
-AK variants
-SIG55X
-AR180
-G36
In short, I don't see the point of it.
Adding a piston is something I don;t see the point of, personally. There are a LOT of other rifles out there that are purpose-build for piston and do it better:
-AK variants
-SIG55X
-AR180
-G36
In short, I don't see the point of it.
I did a lot of umming and ahing over this very question.
Claven2 pretty much nailed it. If you want a piston rifle, get a piston rifle, the AR wasn't designed for piston, and while there are good piston ARs available, DI is a better system for the rifle, and there are better options for piston rifles.
Claven2 pretty much nailed it. If you want a piston rifle, get a piston rifle, the AR wasn't designed for piston, and while there are good piston ARs available, DI is a better system for the rifle, and there are better options for piston rifles.
dangertree
Business Rep
- Location
- NL/ON/FL/PL
Yup.
I think most manufacturers have designed bolt carriers to eliminate this.
For example...
I bought an 8R after watching one go close to 2000 rounds in three days of course/demo without re-lube and without a hickup. New out of the box, with nothing other than an initial clean and one initial shot of lube. No failures. No slowdowns. Ran cool. Cleaned up in minutes. No caked carbon on the bolt. IMO Awesome.
I've never benchrested it to compare accuracy back to back, but I have no problem putting bullets where I want them to go. It certainly seems accurate.
I have put a roller type cam pin in the rifle, they seem like a good idea on piston guns.
I still like my DI guns, but I think I'm a bit of a convert on the pistons. Almost up to 7K through it now. Flawless operation.
There are a lot of articles regarding the piston systems in AR rifles. I've found a article writen by Cameron Hopkins on americanrifleman.org very interesting:
Unintended Consequences of the Piston System
Even if you take the argument of the piston system at face value—that it’s more reliable—you still have the law of unintended consequences to deal with. First, piston guns generate more felt recoil than impingement guns (although that’s not a huge detriment since we’re talking about a 5.56 mm here, a “poodle shooter” as Col. Cooper sniffed).
More importantly, however, a piston system alters the mechanics and timing of an AR in a manner that a growing number of shooters are claiming is harmful to the gun.
There are new systems being developed, tested and marketed now, but generally the problem is that a piston system is attempting to retroactively adapt a bolt carrier that was designed to function with direct impingement.
What we’re seeing are piston systems substituted for the gas tube of an impingement system by simply inserting a piston into the mechanism. The same buffer system is used to return the bolt carrier into battery, the same geometry of the bolt carrier is utilized and the same timing of the cycle rate is retained.
The only difference, really, is that a piston system gives the bolt carrier a mighty whack with a piston instead of blowing gas into it. The geometry is the same. The area of the bolt carrier that is being impacted by the piston is where the gas key would be on an impingement system. In fact, many of the piston systems simply replace the gas key on the bolt carrier with a flat-faced nubbin that is the anvil to the piston’s hammer.
This protrusion is attached to the bolt carrier well ahead (toward the muzzle) of its center of gravity. Going back to see-saw 101, we realize that if a force is applied well in front of a pivot, what happens? The rear tilts.
This see-saw effect is causing bolt carriers to tilt within the receiver, retarding their movement and imparting a non-linear force to the assembly. Stoner did not design the bolt carrier group to be hammered.
Unintended Consequences of the Piston System
Even if you take the argument of the piston system at face value—that it’s more reliable—you still have the law of unintended consequences to deal with. First, piston guns generate more felt recoil than impingement guns (although that’s not a huge detriment since we’re talking about a 5.56 mm here, a “poodle shooter” as Col. Cooper sniffed).
More importantly, however, a piston system alters the mechanics and timing of an AR in a manner that a growing number of shooters are claiming is harmful to the gun.
There are new systems being developed, tested and marketed now, but generally the problem is that a piston system is attempting to retroactively adapt a bolt carrier that was designed to function with direct impingement.
What we’re seeing are piston systems substituted for the gas tube of an impingement system by simply inserting a piston into the mechanism. The same buffer system is used to return the bolt carrier into battery, the same geometry of the bolt carrier is utilized and the same timing of the cycle rate is retained.
The only difference, really, is that a piston system gives the bolt carrier a mighty whack with a piston instead of blowing gas into it. The geometry is the same. The area of the bolt carrier that is being impacted by the piston is where the gas key would be on an impingement system. In fact, many of the piston systems simply replace the gas key on the bolt carrier with a flat-faced nubbin that is the anvil to the piston’s hammer.
This protrusion is attached to the bolt carrier well ahead (toward the muzzle) of its center of gravity. Going back to see-saw 101, we realize that if a force is applied well in front of a pivot, what happens? The rear tilts.
This see-saw effect is causing bolt carriers to tilt within the receiver, retarding their movement and imparting a non-linear force to the assembly. Stoner did not design the bolt carrier group to be hammered.
dangertree
Business Rep
- Location
- NL/ON/FL/PL
^How old is that article?
I don't have a large variety of experience with the AR platform. But I do have an HK MR-308. It's usually the most accurate AR at the range, the cleanest firing gun I own and so far zero problems. No FTF or FTE at all and I've run a large variety of ammo through it. Anything from 150 grain to 168 in most of the major brands including some match grade. Granted I haven't done a carbine course with it. I am usually shooting bench so not a very high intensity use rifle for me, but it's operation has been flawless.
piston AR's
Most everyone has nailed the issue with piston systems dead on.There is only one piston system I personally would consider in an AR platform and that is the POF,as its about half way between the two designs and had had next to Zero problems. A truly well thought out system,but mainly designed for full auto. Check out vidio on their site for further explanationhttp://http://www.pof-usa.com/main.htm
Most everyone has nailed the issue with piston systems dead on.There is only one piston system I personally would consider in an AR platform and that is the POF,as its about half way between the two designs and had had next to Zero problems. A truly well thought out system,but mainly designed for full auto. Check out vidio on their site for further explanationhttp://http://www.pof-usa.com/main.htm
Dirt McGirt
Regular
- Location
- 36 Chambers
Piston sistems be strait up wack. The ar15 be used in battle fo like 50 years with no problems no other rifle can beat it for this. Only noobs need to change it by adding a piston.
TSE_Justin
Offical The Shooting Edge Rep.
Purpose-built piston guns (i.e. not conversions using orig. BCG) work great. However, the added weight and cost puts many users off, and many will not put their guns through enough hard usage to maximize the benefits of a piston system. There are a few companies that make buffers that the carriers can slot into during the firing cycle if you are concerned about carrier tilt.
HK's MR223/416 is probably the smoothest piston AR I have ever shot, so far.
HK's MR223/416 is probably the smoothest piston AR I have ever shot, so far.
Throttle_monkey1
CGN Ultra frequent flyer
I sold my old AR because I was sick and tired of cleaning caked on carbon from the internals. It liked to be run wet, and this was more noticeable the more rounds through her between cleanings.
I just bought an AR lower and will be buying a piston upper when I can find one (hopefully a pWS).
I don't buy too much into the carrier tilt thing, as the gas is still imparting a #### load of force on the carrier to get it to move.
I just bought an AR lower and will be buying a piston upper when I can find one (hopefully a pWS).
I don't buy too much into the carrier tilt thing, as the gas is still imparting a #### load of force on the carrier to get it to move.
If he's going to be spending $2k I would tell him to look into a PWS rifle. I purchased one from Questar and it's in the mail to me right now. I did a lot of research on the PWS MK1 before I bought it and really found no negatives. Everything I read was positive. It is a long-stoke piston rifle, which is pretty cool... sort of like an AR15 with AK47 DNA!
- Location
- 54°52'56"N 112°10'7"W Alpha Bravo
I think if you buy an upper that was designed and built with a piston system from factory it can have it's advantages over a factory DI gun. I think the aftermarket piston kits is where the problem of possible damage and failures occurs. DI is the original, they just require more care and cleaning.
I was also thinking about getting the piston kit for my LMT MRP upper, Im just too lazy, so the less cleaning the better...
I was also thinking about getting the piston kit for my LMT MRP upper, Im just too lazy, so the less cleaning the better...
Spoken like a true noob.
As for the OP's question, there are a few good piston systems out there to look at.. POF, PWS, LWRC, and Adams arms to name a few. Your going to pay more for a good piston than you would for a good DI rifle, and both systems have their strengths and weaknesses. For a first time buyer I would perhaps look at a DI, and then set it up with some quality aftermarket Ambi accessories. But if he is really set on a piston, your options are limited or a proven piston rifle at the 2K mark.
As a lefty AR15 shooter, another option is to simply use a right-handed Ar with ambi controls and simply wear shooting glasses for that 1:1000 chance that a small puff of gass could come near your eyes
Frankly, you should always wear shooting glasses anyhow.
Frankly, you should always wear shooting glasses anyhow.
I would stick to DI AR's personally. I owned a LWRC L6A1 upper and it was heavy and the recoil impulse was something I didn't care for. I sold it at a huge loss and bought a KAC SR15 and haven't looked back. For the weight savings alone I keep the DI AR.
