Are piston uppers really need for M4 carbine config?

[Bushmaster-M4A3]

Just wondering if piston upper is really needed. I know the DI was made for 20" rifle, and it worked out well. The DI problems seem to come up when the military went to 14.5" carbines. So perhaps piston upper addresses this issue with carbine length AR15. From a technical stand point, is piston better than DI for carbines??

[Army Chief]

I think that one could actually make a strong case for the idea that Direct Impingement works quite well for sub-20" systems, whether they are 14.5", 11.5", 10" -- or even something less. The problem is that they are more subject to fouling, of course, and the shorter configurations definitely require more deliberate tuning with respect to gas port sizes, etc. Add a suppressor, and the importance of the initial optimization component looms even larger. Yes, DI carbines can run extremely well, provided they were set up correctly in the first place.

So, is a piston-driven gun "better?" I suppose that depends upon which piston system you're talking about, how you intend to employ the weapon and which DI-related grievance you're attempting to address. Piston configurations offer clear advantages in the technical sense, shoot cleaner, and simplify the system to some degree, but there is also something to be said for the proven track record of DI and the logistics and maintenance train involved with the conventional setup.

The next-generation weapon system will almost certainly involve some kind of ACR/SCAR piston concept, rather than the current DI technology, but should we go a step further and infer that current/conventional AR gas system is inferior or suspect?

40 years of trial by fire suggest that the answer to that must be a resounding "no." We can always learn to build a better mousetrap, but for the moment, DI is still the system that is out there in harm's way getting the job done.

Chief

[RadioActivity]

and round and round we go....

This has been discussed and debated. Search to find out more than you ever wanted to know, and more opinions than you ever wanted to hear.

[Parabellum9x19mm]

if you have to ask, the answer is in all likelihood "NO"

buy a quality DI upper. well produced CAR systems run great, but if you are that concerned, buy a midlength.

save the money - spend it on ammo, mags or training instead

[variablebinary]

Just wondering if piston upper is really needed. I know the DI was made for 20" rifle, and it worked out well. The DI problems seem to come up when the military went to 14.5" carbines. So perhaps piston upper addresses this issue with carbine length AR15. From a technical stand point, is piston better than DI for carbines??


This is one of the larger debates in the AR15 community. Each side has their points.

The anti piston crowd has concerns over the additional weight, the added complexity and thus far the unfounded belief piston guns are inaccurate

The pro piston camp, of which I am a member, accept the undeniable benefits pistons bring to shooters. Piston guns subject the action to very little heat and fouling. Fire 1000 rounds through a piston gun and it looks like a DI gun after a paltry 100 rounds. In addition, piston guns require much less lube and retain their lubrication for higher rounds counts. They work better with short barrels, and suppressors. Pistons are also less sensitive to weak ammo as well

So really its up to you and what you regard as important.

[Jay Cunningham]

Just wondering if piston upper is really needed. I know the DI was made for 20" rifle, and it worked out well. The DI problems seem to come up when the military went to 14.5" carbines. So perhaps piston upper addresses this issue with carbine length AR15. From a technical stand point, is piston better than DI for carbines??

It depends upon the end user requirements.

In general, no. In specific cases, yes. If your requirements have you:

operating a short barreled AR
shooting suppressed
employing a volume of automatic fire
unable to access consistent or quality ammunition

or especially a combination of the above, then a piston upper may really be needed.

[rob_s]

It depends upon the end user requirements.

In general, no. In specific cases, yes. If your requirements have you:

operating a short barreled AR
shooting suppressed
employing a volume of automatic fire
unable to access consistent or quality ammunition

or especially a combination of the above, then a piston upper may really be needed.

Pretty much exactly what I was going to write. Might add something about a necessity for long intervals between cleaning, but when I say "long" I mean literally thousands of rounds as I have several DI guns that have gone 1-2k between cleanings with nothing more than an occasional application of lube through the ejection port..

[T-TAC]

http://www.ar15.com/forums/topic.html?b=3&f=118&t=408880


I found this post very informative. I wron't be buying one.

[rob_s]

http://www.ar15.com/forums/topic.html?b=3&f=118&t=408880


I found this post very informative. I wron't be buying one.

Interesting read actually.

IMHO, the better solution is to go with a rifle that was designed to be piston-operated from the get go.

[No.6]

I read through it too. Think I'll be sticking with DI for the foreseeable future. If I just have to have a piston, then I'll by a new car, or a FAL.

[variablebinary]

I recently went from an LMT MK18 build to an LWRC sorta MK18-ish build with an LMT enhanced bolt and Matech BUIS. I prefer LWRC at this point. It's only had about 300 rounds through it so far, but it shoots great, is accurate and when it came time to maintain the weapon it barely looked fired, with plenty of lube in reserve

It pretty much fixed my biggest beef with the AR15.

Truth be told, I am toying with the idea of dumping all my DI guns except my Colts and going 100% LWRC, with a couple of XCR and SCAR's thrown in for good measure.

[Seth Harness]

Just wondering if piston upper is really needed. I know the DI was made for 20" rifle, and it worked out well. The DI problems seem to come up when the military went to 14.5" carbines. So perhaps piston upper addresses this issue with carbine length AR15. From a technical stand point, is piston better than DI for carbines??


Absolutely necessary? no. Except for the above mentioned attributes.
Otherwise if you like to mess with guns and tinker, its fun to be a part of. If your into that kinda thing, I am. ;)
My $.02, probably not worth much.

[Bachelorjack]

Everyone and their brother is selling one because idiots are buying them like crazy. Most users have no need for them. Capitalism states that for every guy who wants to buy one he will find two guys willing to sell him one.

If you had a need for one, you would know. If you have to ask, you most likely don't have a need for one. This is true of most things.

[Dave L.]

My good friend choked his LWRC around the 2K mark(no cleaning, only adding oil). I've never shot an AR that many times without cleaning it so I can't compare it.
All I know is all machines need maintenance.

[markm]

and round and round we go....

This has been discussed and debated. Search to find out more than you ever wanted to know, and more opinions than you ever wanted to hear.


I can't remember this ever coming up... :confused:

:D

[Parabellum9x19mm]

(negligent discharge)

[TehLlama]

Definitely make a distinction between the dedicated piston uppers and the retrofit systems... the latter have a few engineering issues that have had to be worked on, most specifically carrier tilt.

The LWRC, LMT, HK and POF systems are the only ones I'd personally get a piston setups, as I'd only see a need for the piston system if I was running a suppressed SBR.

BigBore's argument for the DI system does make a lot of sense, but an efficient piston system will still run cleaner and cooler

[SethB]

My good friend choked his LWRC around the 2K mark(no cleaning, only adding oil). I've never shot an AR that many times without cleaning it so I can't compare it.
All I know is all machines need maintenance.

I've gone to 3500 rounds before I had a stuck case, which is something that piston guns are just as susceptible to.

[Cohibra45]

Absolutely necessary??? No.

That said, there has to be a reason that SF boys over in Afghanistan asked to use the HK416, sooooo...

If you are SOCOM over in Afghanistan fighting for your life everyday, then yes 'if' that is what 'you feel confident' using. The DI versions have been around for decades and if you have the time to properly maintain the rifle, then you should be fine.

However, I bought an LMT MRP CQB Piston!!!!!!!! It is my first and only AR, and I am extremely happy with it!!!!!!!!!!:D:D:D It was my choice and I am glad I live in America and could make that choice!!!;)

[Ryo]

Like people said.. it's not necessary. We had it before piston design existed. Some pistons has issues others don't. Haven't used one so can't say how reliable one brand is over another.

[QuickStrike]

Depends. Confidence in a weapon is important to me. I like knowing that my carbine will run even if conditions are not ideal.

I have a LWRC upper that had about 950-1000 rounds through it. It had two FTE's (both had one empty, one live round inside) when I brought it up to the mountains to shoot. Turns out, my friend have been sneaking his gunshow reloads into my mags the entire time. :mad:

These 2 FTE's still bother me. This is after changing out the extractor spring, insert, o-ring and a few hundred more trouble free rounds.

[Broadway]

A quality gun whether DI or Piston will both work. Both need maintenance. My LWRC from the new plant has had >2500 rounds without a hitch. The first 1200 without cleaning during a rifle class. Un-suppressed it's much cleaner.

I completely agree with Rob though. Buy a dedicated system, not a retrofit.

[No.6]

Well it looks like I spoke too soon. Getting ready to buy one of the 12.5" LMT MRP SRB's that Grant has. Dang it all! I hate it when I have some extra cash laying around and there's a new, gotta have one, sitting, just waiting for me and a weak moment....