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Gas piston vs direct impingement: which way to go?


Guest profgunner

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Guest profgunner

Well, I'm just about ready to purchase my first AR and I've been reading a bit on gas piston vs direct impingement. My impression is that the gas piston system is easier to clean but has more felt recoil (not such a big deal in a .223). Are there any other real differences that should be taken into account?

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Basically: Piston guns do not direct carbon back into the receiver, bolt, and carrier. Heat buildup is lessened as hot gasses do not get forced into moving parts. DI guns are more accurate due to

I would enjoy being involved in getting to that point. Dolomite

For all the people that tout the piston as being sooo much cleaner.....maybe, but I have to ask; what the heck are you doing that it makes such a big deal? Do you EVER clean your gun? I'm not saying

I don't see the great improvement from DI to piston, except a little less to clean. It might be of benefit

on a gun that is full auto, but those days are gone. I'm of the opinion "if it ain't broke, don't fix it", and

the AR is fine without it. I'm not knocking the piston guns. I just don't think it is anything spectacular.

Cleaning a DI AR isn't enough of an issue to make me want a piston.

If I were to build another, it would be a side charger, getting rid of that charging handle.

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just go with DI.

I am running two DI guns with Nickel Boron(failzero) bolt carrier groups and have never had a single hiccup....piston operation is really not what the ar was designed to operate with and from my limited experience is just a "me too" fad that shall pass. I'm not saying it doesnt work...just that it is unnecessary and with good parts...you will never have an issue...at least I haven't.

Better yet check this article out....

http://www.slip2000.com/art-swat2.html

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DI

I've had both, neither has had any major issues over the span of 7-10k rounds each.. Buy a quality DI gun. They're lighter, use standard parts, and work just as well.

Mike

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Piston guns have more weight out on the barrel......right where you DON'T want it.

DI guns transfer heat (and gunk) back to the BCG under prolonged periods of fire without cool down.

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I like my piston, I have just seen TOP DOLLAR DI guns fail wwwaaaayyy to much for my liking, that being said I have had a ton of DI Ar's and never any Major problems but then again I never ran them hard, I have ran my piston AR very hard and have yet to have any problems from it, my only complaint as of yet is if you shoot with your thumb looped over the top near the front sight post while shooting it gets extremely hot,not quite AK hot but hot enough you do not want to keep your thumb there without gloves.

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Guest drv2fst

I like the piston AR's better. I've had both kinds. I agree that it isn't really necessary. DI works with good parts and good cleaning. I just like the piston designs better. It make sense to me to keep the heat and carbon away from the moving parts that are feeding the gun ammo.

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For me I would like to try a piston setup but as far as reliability goes I do not see them being any better than the proven DI system. I understand why they should be better but have yet to really seen documentation of a real world difference between the two. A quality DI rifle is going to be as reliable as a quality piston rifle.

A piston system is not going to have more recoil than a DI system. The biggest reason is the piston system adds weight.

There have been a lot of documented DI AR's going thousands upon thousands of rounds without cleaning. Here are some posts detailing a lot of them but one in particular had 4,800 rounds of Wolf, yes Wolf, without cleaning.

Here are a few:

15K rounds of Wolf without cleaning

ppppp_desktop_px_1-tm-tfb.jpg

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Pat Rogers school has a rifle that is rented that has documented more than most:

BCM Complete AR15 Upper and Lower Receivers [2010-01-01] - 03DESIGNGROUP

Here is the most recent article about "Filthy 14". Yes they did finally clean it after firing 26,245 rounds without cleaning.

http://www.bravocomp...thy14_oct10.pdf

So for me piston systems are more snake oil than actually needed because when was the last time any of us fired 25K rounds without cleaning. I'll admit I am not a big fan of cleaning my AR but I have never made it to 25K rounds using a single AR, without or without cleaning. I will say I rarely clean my main gun, probably once a year and after 500-1,000 rounds.

Rather than spend the money on a piston setup I would buy more ammo and practice. I would also buy some of the normal wear parts of an AR. Buy a few disconnects, a few extractor springs, a few hammer springs, a few trigger springs, an extra firing pin, extra gas rings and maybe an extra bolt hold open or two as well as a extra set of hammer/trigger pins. These are the parts I see fail the most with the extractor spring and disconnect being the top two.

I will add something about ammo that I have noticed. American ammo, for whatever reason, seems dry. That is the residue and carbon left behind is dry. This means oil or lubricant needs to be added to some guns to keep them running reliably. Now ComBloc ammo tends to be just the opposite. The residue left behind is almost oily or greasy in consistency. I think this is part of the design and lends to keeping the guns running a bit longer.

Dolomite

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One major benefit the piston has over the DI is for those left handed shooters shooting a right handed AR. There is almost no gases.

For those who are left handed and have shot a right handed AR know what Im talking about. The gases in your eyes is no fun.

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Basically:

Piston guns do not direct carbon back into the receiver, bolt, and carrier. Heat buildup is lessened as hot gasses do not get forced into moving parts.

DI guns are more accurate due to fewer moving parts, lower recoiling mass, and no movement along the barrel.

For your purposes, a piston setup is more hype than reality. You will likely never burn through 500rds in five minutes, melt handguards, or need to shoot a couple of thousand rounds without being able to clean your rifle.

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For all the people that tout the piston as being sooo much cleaner.....maybe, but I have to ask; what the heck are you doing that it makes such a big deal? Do you EVER clean your gun? I'm not saying it isn't cleaner, but unless you're a professional gun fighter I don't see a time where it could possibly make a difference that would make the added expense worthwhile. It's mostly couch commandos spreading that silliness. Clean your gun regularly. You don't have to clean like a Marine, just act like you care about it and will work, so long as you buy a quality setup.

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I'll play devils advocate: :x:

IIRC the AR is the only DI issued gun used by any military in the world. Every other military issued weapon is and has been gas piston. Reason's are pretty obvious. I find it funny the AR guys who spend countless dollars to accessories/fix issues on the AR and then say, "if it ain't broke don't fix it" or "well, it's worked OK for the last 60 years" when it comes to the DI system. :shake:;) NiB coatings, stainless, chrome bolts, "gas busting" charging handles, reworking gas ports, adjustable gas blocks, fancy interior reciever coatings, ...... the list goes on.

Less moving parts arguement - I rarely see someone with an AR concerned with simplicity when they are adding rails, optics, FH, grips, buttstock, contols, etc.

Lighter weight argument - I guess that gets negated once all the above is added on.

Accuracy - the bullet is out of the barrel before the recoil starts unless you have an incredibly long barrrel.

In all seriousness I see it as 6 of one 1/2 dozen of the other. I like piston guns, but I also prefer AK's. If you are getting a piston, the Adams is the best IMO.

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No smith, that's not true brother. Sweden used the AG m/42 Ljungman, Egypt used the Hakim as well as the Rasheed All of which are DI.

Not tying to be a knowitall but it's interesting to note.

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No smith, that's not true brother. Sweden used the AG m/42 Ljungman, Egypt used the Hakim as well as the Rasheed All of which are DI.

Not tying to be a knowitall but it's interesting to note.

The French had the Mas? I think that's the name, but I can't remember.
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No smith, that's not true brother. Sweden used the AG m/42 Ljungman, Egypt used the Hakim as well as the Rasheed All of which are DI.

Not tying to be a knowitall but it's interesting to note.

Current. There were a lot of failed not very good guns in the past. Mas included. ;)

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Guest profgunner

I appreciate all the info. I've got the fever really, really bad now. I've narrowed my choices to 1.) ADAMS ARMS 5.56 X 45 (223) PISTON CARBINE, 2.) OLYMPIC ARMS K3BM4A3, or 3.) Colt SP6920 AR15 Sporter Carbine.

Will probably place my order with BudsGunshop soon. Any input on these three?

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I appreciate all the info. I've got the fever really, really bad now. I've narrowed my choices to 1.) ADAMS ARMS 5.56 X 45 (223) PISTON CARBINE, 2.) OLYMPIC ARMS K3BM4A3, or 3.) Colt SP6920 AR15 Sporter Carbine.

Will probably place my order with BudsGunshop soon. Any input on these three?

For what it's worth, the S&W M&P PS uses the Adams system. I'd stay away from anything with Olympic on it. Especially, a piston system. Also make sure the bolt carrier is chamfered or beveled at the back and the the carrier has the gas key machined into it. Not bolted on to the carrier like a traditional carrier.

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