Gas vs. Piston

[fernset]

Looking to get an AR 15, what should I get. New piston driven or conventional gas driven?
Pros/cons? Pricing? Availability or parts?

I don't have any experience with these but have read the piston driven tend to heat up at the foreend but are easier to keep clean and maintain? Opinions?

[DefensiveCarry.com]

[atctimmy]

I have had no problems with my DI guns. I don't think that the piston guns are worth the money or the weight.

[fernset]

I have had no problems with my DI guns. I don't think that the piston guns are worth the money or the weight.

Piston tend to be heavier?

[Smitty901]

Piston is the way to go. But it will cost a bit more.
Piston stay cleaner and cooler. Only real issue with AR?M4 was keeping it clean. In test the piston ones have been fired as many as 15,000 round without a cleaning.
The Army has been looking at going to the piston design for some time. Wars and all have gotten in the way of making any real changes.
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Huldra » Rifles » Huldra Mark IV 5.56 Carbine

[atctimmy]

Piston tend to be heavier?

Yes, a DI gun has a small hollow tube that leads to the bolt. A piston gun has a piston and a big lug on the bolt that the piston hts. They can be a decent bit heavier and that weight is all in the front end (where it counts the most). They do also get very hot right where your hand is.

But what really deters me is the price. What gain are you really getting for all of that extra money? To me, none.

[peckman28]

You get more weight up front as atctimmy says. The piston guns are excellent if made right, but definitely far more expensive than a comparable DI gun. I personally see no need and would just go with a Colt 6920 carbine. However, if you decide to cough up the extra change for a piston rifle, do your research and get a good one, I don't think you'll be disappointed. Just not worth the extra money to me.

[10thmtn]

For the average civilian, there is probably no difference.

For hard use, I much prefer a piston or op-rod driven design. Heat is the enemy of any machine, and the DI system dumps hot, dirty gases right into the rifle's action. Heat causes metals to expand, burns off lubricant, and causes residue to get baked onto parts like the bolt and bolt carrier.

Rifles with a piston or op-rod keep the heat and residue out of the action. Yes, it weighs a bit more. It costs more. But it is worth it for hard use, IMHO.

Of course, the rifle should be built for that type of system from the start. It's one of the reasons I prefer the Mini 14 (with it's Garand action) to the AR platform.

Now, all the DI devotees will jump up and say that they have fired a gazillion rounds with no issues, and they may be telling the truth. That doesn't change the fact that you should not poop where you eat.

[atctimmy]

For the average civilian, there is probably no difference.

For hard use, I much prefer a piston or op-rod driven design. Heat is the enemy of any machine, and the DI system dumps hot, dirty gases right into the rifle's action. Heat causes metals to expand, burns off lubricant, and causes residue to get baked onto parts like the bolt and bolt carrier.

Rifles with a piston or op-rod keep the heat and residue out of the action. Yes, it weighs a bit more. It costs more. But it is worth it for hard use, IMHO.

Of course, the rifle should be built for that type of system from the start. It's one of the reasons I prefer the Mini 14 (with it's Garand action) to the AR platform.

Now, all the DI devotees will jump up and say that they have fired a gazillion rounds with no issues, and they may be telling the truth. That doesn't change the fact that you should not poop where you eat.

You know what? I completely agree with you in theory, but, in my own experience, I've found no practical difference.

[jonconsiglio]

I have owned them both. I use the heck out of my DI guns and they continue to work. I have a couple SCARs and they are great rifles as well. I had an MRP, LWRC REPR and have an 8" LWRC PSD. If you want very short, then a piston is a decent choice, but for 10.5" and up, i don't see an advantage, and there are periods where I put 3,000 rounds through a rifle in a few days and as long as it's a quality rifle, it's good to go.

There was a member on Lightfighter or m4carbine that took his 12" MRP piston upper overseas and it failed miserably in short order, so he went back to his problem free 14.5" Colt upper. Just ONE example, nothing to base anything on.

I know a number of mil guys that have had serious failures with their HK 416's and switched back to M$ CQBR's as well. For most applications LE, Military or civilian, it won't matter. For very short, suppressed, full auto in adverse weather with a chance of being submerged, then a piston M4 may have an advantage.

The problem with a piston rifle is though the bolt stays cleaner if NOT suppressed, the block gets extremely hot and filthy. Also, the barrel still heats up the same, which is where most failures from overheating are associated. A burnt out, drooping barrel will result from about the same number of rounds, whether DI or piston.

A properly maintained DI rifle will outperform an improperly maintained piston rifle and vice versa. Keep it wiped down every 1,000 rounds or so and keep it wet and either will serve you just fine.

My main isssue with piston ARs is the extreme lack of quality hand guards. I like Daniel Defense and Centurion rails, and there's only one Daniel Defense rail for a piston rifle and it's for the 416. I wouldn't mind owing a 416 10.5" upper, which HK is soon going to release, not the MR556 version.

[tacman605]

For everyday normal use, general shooting you will not notice any difference.

If you plan to train a lot or simply run your gun super hard piston guns clean up easier. Properly lubed the DI guns are fine it all comes down to what you want and can afford.

[jonconsiglio]

For everyday normal use, general shooting you will not notice any difference.

If you plan to train a lot or simply run your gun super hard piston guns clean up easier. Properly lubed the DI guns are fine it all comes down to what you want and can afford.

Hey man! I agree..

Will you be around tomorrow? Message me on Yahoo.

Oh, Colt's new PDW will be available in piston, DI and a hybrid. I don't know anything about it, but I'm interested to see what they came up with.

[tacman605]

Yep will be on will give you a shout. Was gonna go to the strip club but....there wasn't one.

[gasmitty]

Pat Rogers (EAG Tactical) has had the opportunity to evaluate direct impingement as well as piston guns over scores of carbine classes over the past several years. Typical head count is 20-24, typical round count is 1500+ over 3 days. That's 30K rounds witnessed per class. With that kind of exposure, I have faith in his observations. Several manufacturers have provided Pat with test & evaluation guns for him to run through his classes. His typical maintenance schedule is "on condition" - keep it lubed, but no specific maintenance or cleaning unless something fails.

Initially, Mr. Rogers was highly skeptical of the Leitner-Wise piston design, one of the first and most successful on the market, but over time it has earned his respect. However, given the extreme use and intentional neglect, the 'winner' so far remains a Bravo Company DI gun ("Filthy 14") with over 25K rounds through it before it choked.

The Pat Rogers T&E campaign is not comprehensive, and he also doesn't solicit manufacturers to submit their guns. However, he has run several piston as well as DI guns through T&E and so far (thru the end of 2011) none of the piston guns has survived as long as Filthy 14. This doesn't demonstrate "superiority" of the DI design, but rather that the DI design is inherently pretty darned robust. If you're after gun that's reliable in hard use, it's probably more important to look at the credibility of the maker rather then basing your choice on piston vs. direct impingement.

[atctimmy]

If you're after gun that's reliable in hard use, it's probably more important to look at the credibility of the maker rather then basing your choice on piston vs. direct impingement.

That is what I have come to understand as well (although I'm just a regular Joe).

[xplr02]

If it isn't something you are taking out in the field and harsh elements you probably don't need the piston. I myself would rather spend some of the money to get the right caliber. If its just to shoot at the range then 223 is the way to go, I just don't care for it for defense even though everyone will argue with me about that. I would rather have the 6.8 or ever 7.62x39 if I wanted it to defend myself with any day.