The piston-driven AR several years on...

[boltstop]

For several years, numerous manufacturers of AR15s have been answering market requests for a piston driven AR. Ruger produces one, Stag makes a piston driven gun, as does POF and Leitner-Wiese. I think Sig is making one of these rifles as does H&K (although it's unlikely you're "profeshnul 'nuff" to buy one, LULZ).

So what's the story on these guns? We know the military is pretty interested in the H&K gun after fighting for 50 years with the Ljungmann system. Both the FN rifle and the Bushy version of the Masada have gotten some attention, with the FN seeing actual combat with a few units. They are piston guns.

Do these guns have any reduced accuracy over the gas-tube guns? Is there any measurable increase in dependability in the field over the other gun?

Lastly, is anybody considering changing calibers and getting away from the .223/5.56 as a government cartridge?

 

[boltstop]

Re: The piston-driven AR several years on...

Come on, kids, I know a few of you have owned gas-driven guns and have had gas-piston guns for a couple of years.

Is it the answer to the question nobody was asking, or is there a noticeable increase in reliability? Would a user even notice if he wasn't engaged in desert combat?

What about accuracy? The Ljungmann system's claim to fame was that without a big wobbly-piston/tube hanging off the barrel, you'd have less resonance issues and greater accuracy. Are the piston guns any less accurate?

 

[bustin]

Re: The piston-driven AR several years on...

IMO a fad that will die soon.
We have tested several different piston systems, out of those the SCAR was the standout for many reasons, reliability and the fact that it is finely tuned being high on the list, accuracy and quality also higher than most, trigger is poor compared to aftermarket AR triggers. When compared to my personal plain old mid gas 16" 3 gun rig the SCAR is slow, slow to aim and slow to get back on target. I shoot for recreation only when I have time but on average I am 17 sec faster through the stage with my lightweight DI rifle, as long as it is lubed it runs non stop.
The HK being a AR based piston rifle it will point and feel like a DI AR but is a little heavier up front, it could be a closer alternative to the DI AR. Others has serious reliability and accuracy issues, very hard recoil impulses that beat the crap out of the carrier and bolt.

 

[ST42]

Re: The piston-driven AR several years on...

I don't shoot 3G. But, my home built Adams Arms piston upper in .264 LBC is truly a sub MOA rifle out to 750 yards so far. Inside of 500 yards it 1/2 MOA, all day long if I can keep my form up.
I enjoy the heck out of it.

 

[boltstop]

Re: The piston-driven AR several years on...

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: bustin</div><div class="ubbcode-body">IMO a fad that will die soon.
We have tested several different piston systems, out of those the SCAR was the standout for many reasons, reliability and the fact that it is finely tuned being high on the list, accuracy and quality also higher than most, trigger is poor compared to aftermarket AR triggers. When compared to my personal plain old mid gas 16" 3 gun rig the SCAR is slow, slow to aim and slow to get back on target. I shoot for recreation only when I have time but on average I am 17 sec faster through the stage with my lightweight DI rifle, as long as it is lubed it runs non stop.
The HK being a AR based piston rifle it will point and feel like a DI AR but is a little heavier up front, it could be a closer alternative to the DI AR. Others has serious reliability and accuracy issues, very hard recoil impulses that beat the crap out of the carrier and bolt. </div></div>

17 seconds is a lot in a gunfight. The supposed "reliability" of the AK isn't important to anybody but the least educated, most poorly-trained soldier. Seriously - would anybody really claim that the AR is that much harder to maintain than an AK? I KNOW that an AR is much better handling as I have owned both - I will never lay my hands on any AK rifle again as long as I live.

I was thinking that perhaps a DI gun would be higher recoil than the piston gun - but it looks like I'm wrong, huh? Not that my DI guns kick appreciably (even the super-light Carbon 15), but I would expect the .308 gun to be a little harsh.

 

[boltstop]

Re: The piston-driven AR several years on...

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: STS</div><div class="ubbcode-body">I don't shoot 3G. But, my home built Adams Arms piston upper in .264 LBC is truly a sub MOA rifle out to 750 yards so far. Inside of 500 yards it 1/2 MOA, all day long if I can keep my form up.
I enjoy the heck out of it. </div></div>

WOW! Impressive. I'm pretty versed in The Language of The Gun, but I've never heard of .264 LBC. Sounds intriguing. I'll have to look it up. What took you in that direction? What do you like/dislike about this caliber (obviously it stays supersonic for a while, lulz)?

 

[chaos27delta]

Re: The piston-driven AR several years on...

I was wondering the same. how much more accurate if any are DI vs Piston. I myself only have experience with DI. I hear everyone talking about how they love their POF and LWRC and was thinking of purchasing a POF 308. As far as claims of damage to bolt carrier from piston hammering/bashing away at it, have only heard claims. have yet to see pictures or proof. I did read an interesting article about this in Guns&Ammo Combat tactics: Gas Piston AR's why they suck: HOT AIR by Rob Sloyer. Had some interesting information in it, but at the same time you can't always belive what you hear or read. Disreguarding experts opinions or findings on subject is just foolish. Curious to hear what the experts here on this forum have to say about this. LOWLIGHT whats the deal?

 

[Silent]

Re: The piston-driven AR several years on...

I own a LWRC M6A3 14.7" and I can honestly say I prefer it again and again over a DI system. It is sub-moa gun and will run and run even without lube in it. I have dragged it around on multiple hunts and it has yet to let me down... I never really ever had a problem with DI either the only difference I would say is the total amount of time spent cleaning is greatly reduced and I enjoy having an adjustable gas block <<< Just my opinion

 

[sobrbiker883]

Re: The piston-driven AR several years on...

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: boltstop</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: STS</div><div class="ubbcode-body">I don't shoot 3G. But, my home built Adams Arms piston upper in .264 LBC is truly a sub MOA rifle out to 750 yards so far. Inside of 500 yards it 1/2 MOA, all day long if I can keep my form up.
I enjoy the heck out of it. </div></div>

WOW! Impressive. I'm pretty versed in The Language of The Gun, but I've never heard of .264 LBC. Sounds intriguing. I'll have to look it up. What took you in that direction? What do you like/dislike about this caliber (obviously it stays supersonic for a while, lulz)? </div></div>

How versed are you in the language of "bill alexander is a dick that wants the 6.5G to be his forever and ever"? The .264LBC is basically a slightly modified 6.5G chamber that one uses to shoot a Grendel without paying royalties to Alexander.
Best caliber in a small frame AR in my opinion for sport shooting out to 1000 yards or so.

I run a POF in 6.5 Creedmoor and it runs just fine, and shoots half minute as well when I can.
My 6.5CM and another POF in 308 were in the top four at the AZLRPRS April match yesterday, and two 6XC boltguns barely edged us out. Nothing wrong with the accuracy of the platform.

 

[Sebben]

Re: The piston-driven AR several years on...

Might be about to stir up a hornets nest here. Looking at the function of the shot stroke gas piston system of some companies AR platforms from a mechanical stand point they are not much different than the M1A / M14. Now last I checked M1A / M14s have been known for there accuracy and have proved it in many theaters of combat and competitions.

When comparing accuracy between direct impingement and the shot stroke gas piston in the AR platform you're splitting hairs. Some people make piston guns sound like they are all over the paper. Which is not the case. I have seen some amazing shots done by many of you on here with piston and DI guns both producing 1/4 MOA groups.

Most of these people are misinformed and or biased because they have had DI guns work for them in the past and continue to work for them now. It's just human nature to be afraid of change. Don't get me wrong the DI system is a good system It works and has proven to work. But from an engineering stand point and hell just plain logic the SSGP (Short Stroke Gas Piston) is more reliable. Heat is reduced inside the receiver area which anyone who works on cars should know more heat is not a good thing. Fouling in the receiver areas is reduced substantially and in any machine with the tolerances of ARs is also another plus. Cleaning and maintenance is reduced due to reduced fouling and who doesn't want that? Also under sustained fully automatic fire you're not going to melt your gas tube with a SSGP system but that's another subject...

The one foreseeable downside to the SSGP is the added weight... If you want to make a light weight 3 gun or tactical comp gun and feel you can swing an extra 3-4oz then by all means go the DI rout. In the end it's user preference. Look at the facts not opinion, do your homework and decide which weapon system will best fit the situation that you need it for.

 

[lw8]

Re: The piston-driven AR several years on...

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: boltstop</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: bustin</div><div class="ubbcode-body">IMO a fad that will die soon.
We have tested several different piston systems, out of those the SCAR was the standout for many reasons, reliability and the fact that it is finely tuned being high on the list, accuracy and quality also higher than most, trigger is poor compared to aftermarket AR triggers. When compared to my personal plain old mid gas 16" 3 gun rig the SCAR is slow, slow to aim and slow to get back on target. I shoot for recreation only when I have time but on average I am 17 sec faster through the stage with my lightweight DI rifle, as long as it is lubed it runs non stop.
The HK being a AR based piston rifle it will point and feel like a DI AR but is a little heavier up front, it could be a closer alternative to the DI AR. Others has serious reliability and accuracy issues, very hard recoil impulses that beat the crap out of the carrier and bolt. </div></div>

17 seconds is a lot in a gunfight. The supposed "reliability" of the AK isn't important to anybody but the least educated, most poorly-trained soldier. Seriously - would anybody really claim that the AR is that much harder to maintain than an AK? I KNOW that an AR is much better handling as I have owned both - I will never lay my hands on any AK rifle again as long as I live.

I was thinking that perhaps a DI gun would be higher recoil than the piston gun - but it looks like I'm wrong, huh? Not that my DI guns kick appreciably (even the super-light Carbon 15), but I would expect the .308 gun to be a little harsh. </div></div>


Don't confuse maintaining with cleaning. The issues with the M4 are largely serice life related such as bolt lugs failing, gas port and throat erosion, sensitivity to spring weakness, ect. The DI system is great but it isn't forgiving when we get into short barrels and gas ports close to the chamber. It is also ammo sensitive and must be lubed.

Some of this could be fixed with a PIP M4...metal coatings, gas system length, better mags, ect.

In reality, the government generally sucks at product improvement due to the nature of gov contracting and awarding contracts to blind disabled retarded deaf lesbian whatever contractors who subcontract to lowest bidder machinists and end up delivering parts like the Checkmate M9 mags that continue to suck as I type this.

The only way we will ever truly improve the rifle in the world of .gov bureaucracy is to buy a new system.

 

[KillShot]

Re: The piston-driven AR several years on...

+1 on what Sobrbiker883 and Sebben stated above. Furthermore, how old are you boltstop? I'm asking because you seem a little old to be using teenager slang such as "Lulz". It's something I might expect from someone in their early twenties but from someone of your age? Just sayin...

 

[Sebben]

Re: The piston-driven AR several years on...

Problem Solving

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[chaos27delta]

Re: The piston-driven AR several years on...

I'm gonna get yelled at this for sure. Sorry to get off topic on accuracy between the two. Has any owners of a piston AR's experienced any damage resulting from the piston hammering away at the bolt carrier?

 

[Sebben]

Re: The piston-driven AR several years on...

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: chaos27delta</div><div class="ubbcode-body"> I'm gonna get yelled at this for sure. Sorry to get off topic on accuracy between the two. Has any owners of a piston AR's experienced any damage resulting from the piston hammering away at the bolt carrier? </div></div>

Nope. not even a mark. There are no signs of carrier tilt either.

My bolt carrier still has machining marks on it where the piston strikes. but than again it doesn't really strike. It's resting on the carrier to begin with so it really just pushes it.

 

[jakhamr81]

Re: The piston-driven AR several years on...

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: chaos27delta</div><div class="ubbcode-body">I was wondering the same. how much more accurate if any are DI vs Piston. I myself only have experience with DI. I hear everyone talking about how they love their POF and LWRC and was thinking of purchasing a POF 308. As far as claims of damage to bolt carrier from piston hammering/bashing away at it, have only heard claims. have yet to see pictures or proof. I did read an interesting article about this in Guns&Ammo Combat tactics: Gas Piston AR's why they suck: HOT AIR by Rob Sloyer. Had some interesting information in it, but at the same time you can't always belive what you hear or read. Disreguarding experts opinions or findings on subject is just foolish. Curious to hear what the experts here on this forum have to say about this. LOWLIGHT whats the deal?</div></div>

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: chaos27delta</div><div class="ubbcode-body"> I'm gonna get yelled at this for sure. Sorry to get off topic on accuracy between the two. Has any owners of a piston AR's experienced any damage resulting from the piston hammering away at the bolt carrier?</div></div>

Here's your proof demonstrating how hard the BCG can be on the lower receiver from carrier tilt. (Damage is courtesy of an LMT MRP piston)

 

[mackdrvr]

Re: The piston-driven AR several years on...

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: jakhamr81</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: chaos27delta</div><div class="ubbcode-body">I was wondering the same. how much more accurate if any are DI vs Piston. I myself only have experience with DI. I hear everyone talking about how they love their POF and LWRC and was thinking of purchasing a POF 308. As far as claims of damage to bolt carrier from piston hammering/bashing away at it, have only heard claims. have yet to see pictures or proof. I did read an interesting article about this in Guns&Ammo Combat tactics: Gas Piston AR's why they suck: HOT AIR by Rob Sloyer. Had some interesting information in it, but at the same time you can't always belive what you hear or read. Disreguarding experts opinions or findings on subject is just foolish. Curious to hear what the experts here on this forum have to say about this. LOWLIGHT whats the deal?</div></div>

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: chaos27delta</div><div class="ubbcode-body"> I'm gonna get yelled at this for sure. Sorry to get off topic on accuracy between the two. Has any owners of a piston AR's experienced any damage resulting from the piston hammering away at the bolt carrier?</div></div>

Here's your proof demonstrating how hard the BCG can be on the lower receiver from carrier tilt. (Damage is courtesy of an LMT MRP piston)

</div></div>

Another reason as to why I dont own a piston gun.

 

[animalmother85]

Re: The piston-driven AR several years on...

Mere teething issues and also, take into consideration that not all piston rifles are equal. Imagine if it were a new style of vehicle, weather it rolled on tracks, had a rotary or jet engine. All the big manufacturers were making them, to include but not limited to Ford, GM, Dodge/Chrysler, Toyota, so on and so forth. You saw the Daewoo variant broke down on the side of the road within the first year of it's release and then thought, "Nope, no way jose, ain't buyin' one of those new confangnled roe-tuh-ry powered half-track crap piles!" just based off of that. It's like watching myth busters where there are no controls and plenty of variables. I have a gen 1 LWRC with well over 5000 rounds through it as do plenty of others. Not carrier tilt issues, not "exotic" parts broke. A good friend of mine who works for a state counter drug program has a PWS with over 7000 rounds without cleaning it, he also loans it to other departments so they can test it out, also, no issues. Give them time, they'll work out their issues. Is anyone familiar with Glock and what they have gone through in the past?

My "race" gun is DI however.

 

[Anvil]

Re: The piston-driven AR several years on...

I can tell you I carry an HK 416 at work and it is a piston driven system. It is very accurate and very reliable. I will also say before I carried the HK I carried a Colt M4 it to was accurate and dependable as long as I took care of it. The biggest advantage that I see with the piston system is the lack of carbon and gas residue in the action of the rifle. Other than that there is no difference.
I owned a POF 416 SPR for about a year and decided to get rid of it because I decided I could build 2 "nice" AR's for the price of one POF. The POF was a nice rifle though. I feel the piston driven systems are a fad also. I guess one can argue that the piston system requires less maintenance ie cleaning. I don't know about you guys but if I'm gonna spend 2K on a rifle i'm gonna clean it any way even if it isn't "jamming" up on me. So if I'm gonna clean it anyway I'm gonna go with a regular old gas sysystem AR and save some coin.

 

[jakhamr81]

Re: The piston-driven AR several years on...

The piston system guns do not have any advantage that is worth the extra $1000+. Does it run cooler? Sure. Any AR is designed to withstand the high tempratures. A piston ar will still get hot by the gas block as well as the barrel and that is where you could potentially see the POI shifts from the stresses of the barrel. Does the action of a piston gun stay cleaner? Sure, does this result in the more reliability? Only at the high end of rounds fired. If my memory serves me right, when the Army did their testing, mean time to failure for a DI gun was somwhere around 6,000 round; mean time to failure for a piston gun was 8,000 rounds. If you ever find yourself in a gunfight where you have to fire more than 6,000 rounds without a chance to spray your bolt donw with brake cleaner or without at least being able to dump some lube on your gun, you have some serious troubles

 

[tactic-als]

Re: The piston-driven AR several years on...

Probably not having a fraction of the experience of most who commented here I felt the need to reply due to the suggestion that piston guns are a fad. If so, this would imply that their days are numbered and we won't see manufacturers producing piston guns? Just don't see it happening. I have a DI gun and just picked up a REPR. I wanted this particular gun due to it being a piston gun and that LWRC offers an OFF position. If the bolt is locked in the closed position, wouldn't this offer the best one shot accuracy you could ask for in an AR platform. If you want to fire multiple shots as fast as you can, you have that option as well and what kind of accuracy would you expect when doing that? Out of any pros/cons to a piston gun, this and that it would be "less dirty" in the chamber sold me.

 

[KChen986]

Re: The piston-driven AR several years on...

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: chaos27delta</div><div class="ubbcode-body"> I'm gonna get yelled at this for sure. Sorry to get off topic on accuracy between the two. Has any owners of a piston AR's experienced any damage resulting from the piston hammering away at the bolt carrier? </div></div>

The early Gen LWRC M6's had gas keys wobbling loose and shearing from the piston impinging on the gas key. IIRC they tried using a dove-tail design, but that did not work either.

Now they use a one-piece 'coffin' style bolt carrier, which has not had any issues.

I've shot about 5,500 rds through one M6A3, and about 850 through my second one. No issues, pretty damn reliable. They are pricey though. I think that's the primary drawback. Many owners cannot justify the extra expense of the additional marginal benefits (if any).

I'll post pictures of my buffer tube. There's some wear that LWRC attributed to stacking tolerances, but no gouging as seen in the MRP piston above. The grey's supposedly teflon coating.

Also shot 3 rounds at 100 yards on a pastie with irons (their M6A3 front sight has a sharp tip, making it easier to shoot accurately).

For all I know though, maybe I missed the 3rd round on that pastie.

I shot the M6A3 through a 3 day VTAC course, with about 1,500 rounds total fired. No cleaning, No Lube, and the weapon ran well. Also have hit torso-sized steel offhand out to 200 yards.

 

[KevinB-KAC]

Re: The piston-driven AR several years on...

I had two '07 ear Hk416 OTB guns (14.5" and 10.4").
They ran like sewing machines and that vintage of 416 was really the optimal M16FOW piston design.

However I have seen recent endurance testing with several current models, as well as other piston models, and my take is 1) pistons are generally not required for anything 2) if you really really want a piston, go with a non M16FOW platform.

 

[rescueswimmer]

Re: The piston-driven AR several years on...

I'll give you my .02 if you care. If not skip on over this.

I have 2 identical Daniel Defense M4's in Midlength. One is D.I. and the other has a Osprey Defense OPS-418 Gas piston conversion kit. Both rifles are Identical except the Piston kit uses the Osprey BCG. Other than that there identical.

I have about 1500 rounds through the piston gun and about 300 through the DI.

With that being said at a 100 yards shooting 10 shot groups. I get no discernible difference in Accuracy they both shoot MOA if I do my part.

With that being said. Some people worry about carrier tilt. I have 1500 rounds and I see not the slightest bit of carrier tilt just normal wear. Looks similar to my other D.I. Guns.

The recoil pulse is slightly different than the D.I. Gun, I guess that has to do with 2 parts moving rearward instead of one of a DI. gun, but not enough to notice unless your shooting them back to back. Which I did for my test.

There are no debates on this point. Piston guns run cleaner, cooler, and longer between lubes..... You can't debate it. This is why my piston gun gets shot more than my D.I.

I have complete faith in the system and would have no problem using it in a SHTF scenario. With that being said. I do subscribe to the train of thought the more shit you add to anything the more likely it is something could fail.

If the piston kit would break or go down you better have a spare for everything that is proprietary. If you do, no worries if not your screwed until you can get time to back convert your rifle to D.I. With the osprey it would be a matter of about 5 minutes of work, but that is not really practical.

A D.I. Gun has less moving parts so in theory it should be less likely to failure, but its going to transfer heat to the BCG, and get dirty quicker, so more heat and dirt could increase failure rates. So it comes down to personal preference, and what you need it for.

I have an ACR and a SCAR and Im not sure about the poster above ,but for a stock combat rifle, The SCAR stays on target like shooting a 10/22 it's recoil is managed far superior to any other 5.56 rifle I have ever shot. Not to mention is is stupid light.

YMMV.

RS

 

[chaos27delta]

Re: The piston-driven AR several years on...

Thanks guys for the pics and info. I appreciate it

 

[LRS_Ranger]

Re: The piston-driven AR several years on...

I remember seeing this post somewhere before, and as I recall, there are a few thousand rounds fired at the time this picture was taken. Now, I'm no expert, but I would say that any mechanical system has a certain amount of wear in that is acceptable, and once it gets to a certain point, the wear stops and the equipment functions as intended. While there is definitely a bit of wear on the bottom of the buffer tube, it doesn't look like it's at the point that it's keeping the rifle from firing. The threads on the lower receiver look untouched. As a side note, maybe since this is a piston gun the owner ran it for a few thousand rounds without lube? Maybe so and maybe not, but if the wear isn't affecting the function of the gun, then who cares? I'll bet you that the barrel wears out before the gun won't cycle because of "carrier tilt". If it really bothers someone that there are wear marks on their buffer tube, just replace the damn thing for 20 bucks. If you want your gun to be pristine, leave it in the safe and don't shoot it.

 

[fox5]

Re: The piston-driven AR several years on...

I have a few thousand rounds through my Spikes tactical piston upper. Same as the adams system. I love it personally. Breeze to clean.

 

[boltstop]

Re: The piston-driven AR several years on...

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: KillShot</div><div class="ubbcode-body">+1 on what Sobrbiker883 and Sebben stated above. Furthermore, how old are you boltstop? I'm asking because you seem a little old to be using teenager slang such as "Lulz". It's something I might expect from someone in their early twenties but from someone of your age? Just sayin... </div></div>

Nice.

It's this kind of response that reminds me that wherever you go on a gunboard, someone is waiting to evaluate whatever weakness they perceive you present - so they can promptly evaluate it and exploit it for all to see.

Apparently, it makes them feel good and look good to others.

 

[DieTrying310]

Re: The piston-driven AR several years on...

I just caught an article in this month's Guns & Ammo talking about this. It wasn't about longevity per se, just how they handled dirt and grime and crap in their workings. The author took a bunch of piston guns and 2 DGI guns and ran them through a torture test. He repeatedly buried them in sand soaked them in lube, buried them again, dunked them in silt water, so forth and so on.

Not a single one, piston or DGI, ever locked up. Said a couple times triggers would be a bit gritty or stiff, and a couple pistons short stroked the first short or two after being dug up. Other than that, they all worked just fine.

 

[KevinB-KAC]

Re: The piston-driven AR several years on...

Breeze to clean -- piston heads get much more yuck that a DI gun, and realitically most of the new piston guns are taking advantage of new coatings, that did not exist when the M16FOW was created 60 years ago.

We've built DI guns that go 5k without lube suppressed. Yes more expensive -- but not exponentially so, a good DI gun to me is way more pratical than a M16FOW piston.

That said I've used DI guns in harms way several times and never had one fail me...

 

[jakhamr81]

Re: The piston-driven AR several years on...

LRS Ranger, that was my LMT lower receiver in the pic. I had fired roughly 300 rounds at the time it was taken. The gun ran fine at first. Around the 100 round mark, I noticed that the gun seemed to be recoiling very harsh. Not long after, the trigger pin began to come out of place each time I fired it. I installed KNS anti walk pins. The gun continued to recoil harsh, and then very sluggish. I tried heavier and lighter buffers, but nothing seemed to work. Around the 300 round mark, the gun just quit cycling and became a bolt action. I noticed metal shavings in the lower receiver and that keyed me into the damage of the reciever extension. I took the picture and sent it to LMT along with a few others. Their response was that the problem may be the KNS pins I installed or the magpul pistol grip, as I had done some "custom" work to the gun.

Long storry short I shit canned that upper and replaced the worn out receiver extension.

To answer your response, I am not concerned with how my firearms look, only that they are functional and get the job done. This LMT MRP did neither. The receiver extension is not designed as. A wearing part, and should not have to be replaced. Even if it is only $20 bucks.

You should try to avoid speculating in the future

 

[Aries64]

Re: The piston-driven AR several years on...

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: chaos27delta</div><div class="ubbcode-body"> I'm gonna get yelled at this for sure. Sorry to get off topic on accuracy between the two. Has any owners of a piston AR's experienced any damage resulting from the piston hammering away at the bolt carrier? </div></div>
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: KChen986</div><div class="ubbcode-body">The early Gen LWRC M6's had gas keys wobbling loose and shearing from the piston impinging on the gas key. IIRC they tried using a dove-tail design, but that did not work either.

Now they use a one-piece 'coffin' style bolt carrier, which has not had any issues.</div></div>
<span style="font-weight: bold"><span style="font-style: italic">chaos27delta</span></span> -

Many years ago I bought a <span style="font-style: italic">"Pre-Ban"</span> A2 Bushmaster 16" Shorty 1:9 (twist). A 16" barrel AR isn't a precision rifle, but 2 MOA or less with a TA11 is good enough out to 600 yards. About 14 months ago I bought a LWRC M6A2-S Upper (1:7 twist). I'd say it is at least as accurate as my Shorty was and could shoot 1 MOA with a different optic.

The M6A2-S also has a true mid-length gas system (unlike most 16" ARs') and shoots quite smoothly in comparison with the Bushmaster Shorty which had a Carbine-length (7") gas system. And regardless of what you hear about other piston ARs' the LWRC is a world apart in fit and finish compared to all other manufacturers'.

Below are a couple of photos' of LWRC's monolithic (one-piece) bolt carrier assembly as mentioned by <span style="font-style: italic">KChen986</span>. The photos are borrowed from <span style="font-style: italic">johnlee</span> as John's photos are nice and clear so I saw no point in a re-shoot.

<span style="font-weight: bold">NOTE:</span> <span style="font-style: italic">The second photo shows gas rings installed on the bolt - they're unnecessary on the LWRC Piston System which uses a standard bolt and can be run with or without rings.</span> I run my bolt without rings.

<span style="font-weight: bold"><span style="font-style: italic">LWRC Monolithic Bolt Carrier Assembly:</span></span>

<span style="font-weight: bold"><span style="font-style: italic">Gas Block on the LWRC M6A2-S "Stretch":</span></span>

I've also had the stock on and off my M6A2-S's lower several times, and I don't have any gouging or noticable wear to the finish on the I.D. of the buffer tube.


Keith

 

[jakhamr81]

Re: The piston-driven AR several years on...

... and by the way LRS Ranger, even though it was a piston gun, I still used a light coat of lube... so much for that theory.

 

[BERTMAN77MK2]

Re: The piston-driven AR several years on...

(+1 on what rescueswimmer said) I converted 1 Colt to Osprey piston system and see no difference in 14.5" barrel accuracy out to 300meters--thus I prefer this piston gun over my DI for 3-gun
---however I have asked the expert gunsmiths and shooters on this site in past threads and it was explained to me that the DI
guns were more accurate at long range because of less stuff hanging off the barrel--however I am sure if the harmonics are right the accuracy issue would be nil---kind of like the argument of cut-rifled barrels versus button-rifled--both have their plus's and minus's---as a side note 1500rds and no discernable damage from carrier tilt or anything else for that matter---also PWS makes a special(improved)buffer tube for those that worry about it (Brownell's has 'em)

 

[bustin]

Re: The piston-driven AR several years on...

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Sebben</div><div class="ubbcode-body"> Might be about to stir up a hornets nest here. Looking at the function of the shot stroke gas piston system of some companies AR platforms from a mechanical stand point they are not much different than the M1A / M14. Now last I checked M1A / M14s have been known for there accuracy and have proved it in many theaters of combat and competitions.

When comparing accuracy between direct impingement and the shot stroke gas piston in the AR platform you're splitting hairs. Some people make piston guns sound like they are all over the paper. Which is not the case. I have seen some amazing shots done by many of you on here with piston and DI guns both producing 1/4 MOA groups.

Most of these people are misinformed and or biased because they have had DI guns work for them in the past and continue to work for them now. It's just human nature to be afraid of change. Don't get me wrong the DI system is a good system It works and has proven to work. But from an engineering stand point and hell just plain logic the SSGP (Short Stroke Gas Piston) is more reliable. Heat is reduced inside the receiver area which anyone who works on cars should know more heat is not a good thing. Fouling in the receiver areas is reduced substantially and in any machine with the tolerances of ARs is also another plus. Cleaning and maintenance is reduced due to reduced fouling and who doesn't want that? Also under sustained fully automatic fire you're not going to melt your gas tube with a SSGP system but that's another subject...

The one foreseeable downside to the SSGP is the added weight... If you want to make a light weight 3 gun or tactical comp gun and feel you can swing an extra 3-4oz then by all means go the DI rout. In the end it's user preference. Look at the facts not opinion, do your homework and decide which weapon system will best fit the situation that you need it for. </div></div>
Compare the number of highpower shooters using a AR to those using a M1A and then ask yourself why.
I have had several M1As and double lug M21s, they do not compare with the consistant accuracy of the AR.

 

[jakhamr81]

Re: The piston-driven AR several years on...

If you are saying that cleanliness is the biggest benefit of a piston system, then I say to you this; I have to clean my DI gas ARs not because of carbon fouling, but because I need to clean the copper fouling out of the bore, maybe every 300-500 rounds or so. No piston gun is immune from copper fouling in the bore. All you need to do with a DI system is keep it lightly lubed to keep it working. Cleaning the BCG and action is no sweat either:

1. Disassemble weapon/ BCG
2. Spray BCG and parts down with brake cleaner, quickly scrub with nylon brush if needed.
3. Spray inside of receiver with Brake cleaner, Scrub with nylon brush if needed.
4. Wipe down with rag, lightly lube all parts, and resemble.

It should not take more than 5 minutes to do a quick functional cleaning. This small amount of maintenance will allow any DI AR to run for thousands of rounds.

IMO all moving parts should have some lube on them even in a gas piston system, this will save on wear and tear on the moving parts. Wet lubes can attract sand, dust, dirt, etc... So unless you are using a new high speed dry lube or some type of Teflon based lube (which you could also use on a DI gas AR) the lube on your gun will attract dirt and sand; therefore, a gas piston AR is not in any way superior in a desert environment. You can bury a DI gas AR in the sand, pull it out and shoot it just like they do to the gas pistons in those sales pitch videos.

Are their some gas piston guns out there that run great and are capable of excellent accuracy? Sure their are.

Is their any advantage to a gas piston AR over a DI gas AR? NO, not IMO; especially not an advantage that is worth an extra $1,000+.

 

[Sapper524]

Re: The piston-driven AR several years on...

Having shot both, ill stick to the DI system. Less moving parts. I would never go with a conversion kit. The gas key replacement is a bad idea, that come loose and you might need a trip to the ER. The whole accuracy and dependability argument is moot. Like all firearms, you build a $600 AR your not going to get a MOW rifle. You get up in the $1200 and up range, with a quality machined BCG you will get results. The AR was designed as a DI system, if you want a piston system get a piston system design like a M1A. My thoughts on the subject ......

 

[gmnealusn]

Re: The piston-driven AR several years on...

Honestly, the only benefit that I have seen with my piston AR over my DI AR is that the bolt, carrier, and fire control group does not recieve as much heat or carbon fouling. The accuracy of both guns is pretty much equal and the piston upper only weighs a little more. In fact the only reason I bought my LMT piston upper is that it has the ability to swap out calibers and barrels quickly with repeatable accuracy.

 

[VKC]

Re: The piston-driven AR several years on...

I have both a LWRC M6A2 5.56 and POF 6.5 Creedmoor.

I've found no decrease in accuracy with piston rifles. In fact I've found mine to be more accurate than the DI rifles that I've shot, but I don't think this is a fair comparison since the quality of the DI rifles that I've shot aren't the same and some of the calibers were different, so I'll just leave it at just no decrease in accuracy.

I think much of the improvement in accuracy also has to do with other factors besides piston systems, such as barrel, tolerances in parts, etc. Guns in general, piston and DI, have all improved in accuracy over the years, or at least are more widely available at more reasonable prices.

Reliability is similar or better with piston rifle depending on how much you shoot in between cleaning.

I definitely do find less fouling and thus easier cleaning with piston vs. DI. Plus, LWRC & POF guns come with NiCorr or NP3 coating which makes a difference as well.

For me at least, I feel like the time I save cleaning my rifles is worth the extra money, but that is just me.

Yes, I think unique and extra piston parts are a concern, but LWRC & POF have great reputations and take care of their customers quickly without undue hassle. I would be very surprised if LWRC and/or POF go out of business in my lifetime, and I can't find parts anywhere. I'm not delusional enough to dream up armageddon scenarios or believe that I'm a zombie hunter.

 

[chainring]

Re: The piston-driven AR several years on...

If you have carrier tilt issues, get an LWRC. I can't speak for any other maker, but my LWRC rifles are excellent machines.

Here's today's pic of my A3 that has about 1500 suppressed rounds through it so far. I cleaned it...last May, I think.

 

[KillShot]

Re: The piston-driven AR several years on...

Here is what Frank, from POF*USA, has done about the bolt carrier tilt issue with the POF rifles. This video is rather lengthly at nearly 7 minutes but the part to watch starts at the 4 minute mark.

<object width="425" height="350"> <param name="movie" value="http://www.youtube.com/v/TbVjLZfXp8U"></param> <param name="wmode" value="transparent"></param> <embed src="http://www.youtube.com/v/TbVjLZfXp8U" type="application/x-shockwave-flash" wmode="transparent" width="425" height="350"> </embed></object>

 

[AJB]

Re: The piston-driven AR several years on...

I own an LWRC 10.5 M6A2. I really do like it. My only gripe is that is much heavier than most DI uppers. Does it save me time on cleaning, yes, but they are much more expensive. I think for the same amount of $ I could be just as happy with a Noveske DI, but I dont regret the purchase.

 

[LRS_Ranger]

Re: The piston-driven AR several years on...

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: jakhamr81</div><div class="ubbcode-body">LRS Ranger, that was my LMT lower receiver in the pic. I had fired roughly 300 rounds at the time it was taken. The gun ran fine at first. Around the 100 round mark, I noticed that the gun seemed to be recoiling very harsh. Not long after, the trigger pin began to come out of place each time I fired it. I installed KNS anti walk pins. The gun continued to recoil harsh, and then very sluggish. I tried heavier and lighter buffers, but nothing seemed to work. Around the 300 round mark, the gun just quit cycling and became a bolt action. I noticed metal shavings in the lower receiver and that keyed me into the damage of the reciever extension. I took the picture and sent it to LMT along with a few others. Their response was that the problem may be the KNS pins I installed or the magpul pistol grip, as I had done some "custom" work to the gun.

Long storry short I shit canned that upper and replaced the worn out receiver extension.

To answer your response, I am not concerned with how my firearms look, only that they are functional and get the job done. This LMT MRP did neither. The receiver extension is not designed as. A wearing part, and should not have to be replaced. Even if it is only $20 bucks.

You should try to avoid speculating in the future </div></div>

Ok, I stand corrected. I've read any number of "carrier tilt" threads where the poster was bitching because their buffer tube had wear after a ton of rounds.. I agree that if you were getting wear like that after 300 rounds combined with poor functioning, you have something wrong with the equipment. I would say that you got a lemon. Although they didn't admit a faulty product, did they still take care of you?

 

[cz777]

Re: The piston-driven AR several years on...

ok please add the ''new'' buffer tube by PWS which will help stop the damage ..all weapons have weakness and strengths -total of sum is best made and cared for will win but all is man made ,all can fail !

 

[eleaf]

Re: The piston-driven AR several years on...

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: boltstop</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: STS</div><div class="ubbcode-body">I don't shoot 3G. But, my home built Adams Arms piston upper in .264 LBC is truly a sub MOA rifle out to 750 yards so far. Inside of 500 yards it 1/2 MOA, all day long if I can keep my form up.
I enjoy the heck out of it. </div></div>

WOW! Impressive. I'm pretty versed in The Language of The Gun, but I've never heard of .264 LBC. Sounds intriguing. I'll have to look it up. What took you in that direction? What do you like/dislike about this caliber (obviously it stays supersonic for a while, lulz)? </div></div>

It's a bastard child of the 6.5 Grendel.

 

[eleaf]

Re: The piston-driven AR several years on...

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: bustin</div><div class="ubbcode-body">
Compare the number of highpower shooters using a AR to those using a M1A and then ask yourself why.
I have had several M1As and double lug M21s, they do not compare with the consistant accuracy of the AR. </div></div>

Which has nothing to do with the accuracy of a DI gun over a piston driven gun.

It's like saying that a single action pistol is better than a double action pistol because "my 1911 .45 outshoots my S&W 357".

 

[jakhamr81]

Re: The piston-driven AR several years on...

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: LRS_Ranger</div><div class="ubbcode-body">

Ok, I stand corrected. I've read any number of "carrier tilt" threads where the poster was bitching because their buffer tube had wear after a ton of rounds.. I agree that if you were getting wear like that after 300 rounds combined with poor functioning, you have something wrong with the equipment. I would say that you got a lemon. Although they didn't admit a faulty product, did they still take care of you? </div></div>


Did they take care of me??? NO! They tried to imply that I somehow caused that problem with all of my radical modifications (KNS anti-walk pins, Magpul grip, and Magpul BAD lever). That is why I shit canned that upper and will no longer deal with LMT... They are either incompetent or complete pricks; either way, that is not a manufacturer that I will chooses to do business with. I have found several manufacturers that have earned my repeat business.

 

[PLeighton]

Re: The piston-driven AR several years on...

After several years of research the conclusion I always come to is that all the GP system does is keep the BCG a bit cleaner and degrade accuracy.

GP vs. DI argument is pretty old, but the consensus agrees on at least these points:
- GP overall is a cleaner running platform.
- GP increases reliability if you don't take into account setting up a DI for high reliability.
- GP does not have near the parts availability or standardization of DI.
- GP is inherently less accurate due to the additional reciprocating mass in a separate plane than the barrel and additional pressures exerted on the barrel assembly.
(The accuracy claim is old and if you have any doubt, ask George Gardner of GA Precision or Jered Joplin on American Precision Arms.)
http://www.snipershide.com/forum/ubbthreads.php?ubb=showflat&Number=2307383
*BOTTOM LINE*
Gas Piston is perfect for people that like to have a clean gun but don't like spending two hours to get there.
All bets are off though when you add a suppressor.

The two solutions that I have seen work the best is a "Switch Block" type setup and / or appropriate rifle setup.
What is appropriate rifle setup?
I would consider appropriate rifle setup as keeping the BCG and locking lugs well lubricated in a quality product like Mobil-1 or SLIP 2000 EWL.
It is also appropriate to use a heavy buffer and spring to slow down the action.
(This allows more dwell time for gas to escape the bore / chamber.)

As for jakhamr81 's experience with LMT, It is unfortunate, but I can assure you that LMT is not as you say "incompetent".
Their history with NSW and CRANE is well known and their record with the military is exceptional.
LMT is also know for their innovative products and outstanding quality.
Anyone can have a bad day and sometimes a customer's approach has significant bearing on the direction of a customer service issue.
I certainly don't blame you for not wanting to do business with any company after having a bad experience, but your experience is not a very common one.

 

[adam1122]

Re: The piston-driven AR several years on...

I was concerned with carrier tilt issues.....so I went with the big money LWRC REPR system with a 20 inch barrel in .308. In the near future I will pick up several smaller barrel lenghts and scopes/sights for different types of work. I have not experienced a single failure of any kind in my lwrc and it only takes 5 min to clean the barrel to get rid of any coppper fouling.

Now, comparing my LWRC to my Armalite Ar-10 and I will say there is no comparison in which gun is easier to maintain and operate. LWRC hands down. My Armalite (gun only .308 cost about $1500)...the LWRC Repr (gun only cost about $3800). The parts, especially the bcg on the lwrc are made better....no doubt about it. Both guns are accurate for their intended shooting distances.

However, if anyone expects massively better accuracy from a DI gun vs a piston gun they may want to do some more research...especially don't ask that question on this forum or you will get hammered. Both well built DI and piston guns can shoot sub-moa groups, and both of them are now very close to being able to shoot just as good as any high quality bolt gun (I said close not exactly). The LWRC is about as close to a bolt guns accuracy that I have seen commerically available when the gas system is turned all the way off and the bolt then has to be manually cycled - talk about sub moa groups.

Buy good quality parts in either system and they just work. Eugene Stoner was a friggin genius who was way ahead of his time when he designed the M16. For the record, you cannot expect to buy a $900 AR system of any kind and not get some kind of failure of some kind. Thats why you dont see LE/military/PMC guys carrying crap guns....they all have gear that runs in the several thousands of bucks. Makes me jealous that I no longer have access to free ammo and have to pay for it to shoot.

Hope I stirred up the hornets nest good this morning. Just wound up because I get to go do some sighting work on LWRC's burris fastfire ii sight I have on it....

I love spending money on weapons and ammo with no wife to complain at me about it!

 

[KChen986]

Re: The piston-driven AR several years on...

Here's an interesting test on accuracy done by Molon on M4C:

http://www.m4carbine.net/showthread.php?t=32479&highlight=molon