Direct impingement v. Gas piston

[Partychief67]

This is a direct quote from another forum:

"direct impingement is a terrible system. the hot gas contacting the bolt burns away all the lubrication, weakens the internal parts, and leaves you with an unreliable, jammy weapon"

I would accept the statement as pure B.S. except for articles like this:

Ruger SR-556 Gas Piston/Op-Rod AR-15 Carbine/Rifle: Ruger Enters the Piston-Driven AR Fray

So what do everyday shooters say?

 

[Texas1911]

DI guns just require more cleaning, that's about it really.

Gas piston can be more reliable, but generally speaking the DI guns will run for thousands of rounds with simple motor oil for lube.

Most of the gas piston vs. DI is marketing. If you go to the range and shoot a couple hundred rounds, you don't need a gas piston. If you are buying a gun to drag off to Afghanistan or use in competition / training, then I would look into a piston.

For what it's worth, the piston guns are coming down in price, and that is the way of the future. I will probably buy an LMT CQBP here in the next year.

 

[jdh]

Just posted this in another forum:

If it needed a piston system Stoner would have designed it that way!
If I would have wanted and AK I would have bought an AK.

I have been issued some for of the AR since 1975. None of them have had pistons. All of them worked.
For the past 10 years I have been an instructor for an agency that issues pre-M4 M16A2 carbines. These
are some of the most neglected and abused examples of the breed. If they do start to balk on the range
spray a little oil in the ejection port and back to work they go.

I just don't see the need for the added expense and complexity the piston "upgrade" adds.​

 

[WhoDat]

Pistons add a half pound, and a couple hundred dollars. The weight is a serious concern, for me, as I actually like to carry some of my rifles in the field for hunting. Nowadays, an M4 can get pretty dang heavy, with: rails, optics, etc... Piston kits seem to add about a half pound, much of it in the front-end (the piece I swing to shoot) of the rifle, and that's noticeable.

Not worth it, for me. ARs in DI are proven killers. And I like maximum interchangeability, across my dozen or so AR rifles.

But yes, there may be 1 or two kits in my future... just to play with.

 

[smschulz]

DI guns just require more cleaning, that's about it really.

Gas piston can be more reliable, but generally speaking the DI guns will run for thousands of rounds with simple motor oil for lube.

Most of the gas piston vs. DI is marketing. If you go to the range and shoot a couple hundred rounds, you don't need a gas piston. If you are buying a gun to drag off to Afghanistan or use in competition / training, then I would look into a piston.

For what it's worth, the piston guns are coming down in price, and that is the way of the future. I will probably buy an LMT CQBP here in the next year.

I agree on pretty much all stated above.
I like and prefer the piston but it is not necessary.
The main problem is pricing (which is going down) and the limitations of handguards when retrofitting.
All of the the backlash against the piston model is just as much BS.
Eventually ... pretty much ALL... AR's will be piston, IMO but this evolution will take time...but i's comin'.

 

[Dawico]

The piston setups are for hard use in bad environments, or use with a suppressor. My AR gets 4x as dirty with a suppressor on it, so I switched it to a piston setup. It now only gets as dirty as a regular AR with no piston. I can see the need in that scenario, but for the general shooter going to the range once a month with 200 rounds, it is not required.

I agree with the marketing ploys. But, if they can convince people to buy on that reasoning, good for them. I am all for the innovation and improvement of the system.

 

[Partychief67]

So is that SR-556 worth the price or hold out for a retrofit kit? Can anyone point me towards any good kits for a Colt?

 

[smschulz]

So is that SR-556 worth the price or hold out for a retrofit kit? Can anyone point me towards any good kits for a Colt?

Adams Arms - Carbine LE

 

[Partychief67]

Adams Arms - Carbine LE

Thanks for the info! $379 is two weeks worth of lunch money though... LOL

 

[M. Sage]

This is a direct quote from another forum:

"direct impingement is a terrible system. the hot gas contacting the bolt burns away all the lubrication, weakens the internal parts, and leaves you with an unreliable, jammy weapon"

I would accept the statement as pure B.S. except for articles like this:

Ruger SR-556 Gas Piston/Op-Rod AR-15 Carbine/Rifle: Ruger Enters the Piston-Driven AR Fray

So what do everyday shooters say?

It's over-simplified and almost complete BS to begin with. DI systems have been around a lot longer than the Stoner system. The Ljungman AG-42 rifle made in Sweden was a kick-ass rifle. So good that the Egyptians made a version they called the Hakim. If a desert-bound nation can adopt it and like it, then it can't be so bad, now can it.

There are negatives to DI - carbon where you don't really need it, on the AR which is lubrication-sensitive the DI blows the lube out (use grease to get around this. The use of oil makes so little sense to me). The rifle that gives DI a bad name is the M4. That short-ass gas system is the cause of many problems that simply aren't an issue on the longer gas systems. The shorter system picks up hotter gases that have more unburned powder, resulting in more carbon, at higher pressure, resulting in higher barrel wear. There can be a couple of other issues with the shorter system, but they're not as huge... Overall, DI isn't a huge disadvantage. There are some advantages to it, too - higher mechanical accuracy through less barrel flex for one thing. Lower recoil impulse because of lower reciprocating mass.

A piston gets rid of these disadvantages (as minor as they tend to be with the longer systems), but comes with some of its own disadvantages - recoil impulse is different and can be higher because of the increase in reciprocating mass. Mechanical accuracy can actually be lower because when the gas pushes against the piston, it also pushes against the barrel, causing it to flex. The cost is a factor, for sure - look how much more expensive piston systems are.

IMO, for an average shooter piston ARs do not even come close to the break-even point if you look at it as a cost/benefit issue. There are uses for piston systems - very short rifles, and especially rifles meant to be run suppressed so that you can run an adjustable gas system (again, shorter DI gas systems make this even more of an issue). Oh, and full-auto rifles, especially carbine-system rifles, that see loads of FA use with long bursts, long cleaning intervals and high round counts - if you dump mag after mag after mag in FA until your barrel glows, a piston is probably for you. IMO, the average shooter would be way further ahead simply buying a full-length rifle, or if you want a carbine, getting a carbine barrel with full-length gas system on it. I'd love to see the carbine-length system disappear from 16" rifles on the civilian market completely. The only reason the military went with the short system on the carbines was so those rifles would be capable of using existing bayonets. Again IMO, the military should redesign the bayonet mounting system for the M4, put a full-length gas system on it and issue new bayonets for these rifles.

One more advantage that the full-length system has over the carbine system is sight radius. The carbine gas system gives you a sight radius roughly equal to that on the AK. Weak sauce. If you go with a full-length gas system, you get the sight radius of an M-16 with the shorter barrel of a carbine, and much better cleanliness and reliability than the carbine system would ever offer.

 

[Partychief67]

Thank you M.Sage, that is the kind of well researched info. that keeps me coming back to this forum!

 

[Texas Patriot]

If you want a piston .223 rifle, you should consider one of the new Ruger Mini 14 models. They are much more accurate than their prececessors, and as Minis go, they are all piston driven. Totally reliable, more accurate than the older ones, and now you can get good mags, (factory Ruger mags at a decent price, though still not as cheap as AR mags) and a fun gun to shoot and hunt with. Almost all other assault type weapons are piston driven in one fashion or the other. So, the AR is just finally realizing what was known for the last 80 years or so.

All that being said, I have 4 DI ARs and love them all.

 

[ftw13]

gas piston....in 5.45x39

 

[SIG_Fiend]

AR's can run just fine on DI, they just need a bit more love a bit more regularly to keep running. The one thing I will say is this. How many other guns currently out there, or that have been made within the past 50yrs, use a DI system other than the AR variants? I can't think of a single one. Almost every other similar semi-auto rifle I can think of is a gas piston. That says a lot to me as well. Oh, and the LMT MRP gas piston is quite possibly about the most perfect AR out of the box of all time. If I can afford one later this year, I will buy one too.

 

[M. Sage]

AR's can run just fine on DI, they just need a bit more love a bit more regularly to keep running. The one thing I will say is this. How many other guns currently out there, or that have been made within the past 50yrs, use a DI system other than the AR variants? I can't think of a single one. Almost every other similar semi-auto rifle I can think of is a gas piston. That says a lot to me as well. Oh, and the LMT MRP gas piston is quite possibly about the most perfect AR out of the box of all time. If I can afford one later this year, I will buy one too.

The Hakim was produced as late as the '60s.

Also, DI rifles with good barrels are showing accuracy potential at least as high as bolt actions do.

 

[GigAg04]

I have the LMT CQB MRP you all speak of. It is amazing. Mine is a 16" and it is heavier than my counterparts' (I work for a local PD) rifles, but it shoots great.

The military standard trigger is a tad heavy for me, but I looooooove this weapon. I already put on my larue grip and mount for my Aimpoint. I put some XTM rails on it and a streamlight. The cheek weld on the sopmod stock is a great feature as is the monolithic upper. It's G2G imo for my next zombie uprising call.

I got it in College Station from Champion's who got it to me for $100 less than what the LMT site had them for.

 

[IXLR8]

After owning a DI AR for a year, I can say I don't like the system. Sure it works, but I don't want something that I need a can of spray to keep firing.

My dream rifle is a POF. No lube, and clean as a whistle even with dirty powder.

POF - take a look!

Expensive? Yes, very....

 

[40Arpent]

After owning a DI AR for a year, I can say I don't like the system. Sure it works, but I don't want something that I need a can of spray to keep firing.

My dream rifle is a POF. No lube, and clean as a whistle even with dirty powder.

POF - take a look!

Expensive? Yes, very....

I am not sure which DI gun you are running and in what kind of conditions, but for general range use and toting around in some pretty dusty regions of S. Texas (ranch), my Colts have been very reliable and dependable with decent cleanings between uses. Don't get me wrong, though, I am a big fan of piston guns....just haven't gotten one yet. The LMT MRP is next on my list.

It may just be internet rumor, but I have heard of some quality issues with POF relatively recently, so you may want to do some homework before you take the plunge.

 

[M. Sage]

After owning a DI AR for a year, I can say I don't like the system. Sure it works, but I don't want something that I need a can of spray to keep firing.

My dream rifle is a POF. No lube, and clean as a whistle even with dirty powder.

POF - take a look!

Expensive? Yes, very....

A can of what to keep it running? The lighter the oil you use, the less it's going to stay put. Use grease on that sucker and it becomes a very reliable rifle. One of my buddies commented that his kids both knew SPORTS by heart because of how his AR ran. He started lubing with grease and suddenly his daughter commented that the rifle was actually fun to shoot.

 

[SC-Texas]

Gene stoner's DI is a gas piston design.

What is the issue?