thinking of upgrading

[sniper7]

I will only chime in that the ar/m16 has done quite well for about 50 years now. no point in changing something that ain't broke.

[Hoosier]

I will only chime in that the ar/m16 has done quite well for about 50 years now. no point in changing something that ain't broke.

Yet another entirely philosophical difference between us, I see.

IMHO the piston guns keep a lot of the heat out of your bolt carrier group, and makes cleaning an order of magnitude easier.

Also those failure states related to gas operated rotating block are eliminated, for example if the three washer gaps somehow align.

AK-47 has been a piston driven design and predates the Armalite AR-15, so perhaps it's more a matter of "If you had a bad design choice in the 50's, why keep it through to this century?"

H.

[Byte Stryke]

AK-47 has been a piston driven design and predates the Armalite AR-15, so perhaps it's more a matter of "If you had a bad design choice in the 50's, why keep it through to this century?"

H.

You are assuming of course that the AR Design is bad.
While I Agree that the AR system has its faults, I believe they all do.
(Seriously, ring alignment?)

Without getting all long and drawn out here I think we can agree on that and group hug.

[spyder]

I don't think there is anything wrong with the design, but if you can make something better, why not do it? I can see the arguement of someone saying that they don't want to spend the money on it because theirs works just fine for them, but I don't think this is a case of "fixing something that isn't broken". It is just wanting to improve on an already good design.

[Hoosier]

I'm just not a huge fan, I guess. Seems overly complex.

I would like to learn more about the internal operation of these guns though. For example, the gas actually rotates the bolt to unlock it, right? How's that accomplished in a piston driven gun?

I should Google around for some cutaway animations, like that Glock one.

Oh, and the show "Factory Made" had a look at how the LWRC R.E.P.R. being manufactured. Solid billet, pretty sweet forearm attachment with continuous rail, and the charging handle is in a far better position.

http://www.lwrci.com/p-120-repr.aspx

Looks like a pretty sweet rifle.

H.

[ChunkyMonkey]

I have adam arms piston uppers. Here is the cut out animation...

[BPTactical]

I'm just not a huge fan, I guess. Seems overly complex.

I would like to learn more about the internal operation of these guns though. For example, the gas actually rotates the bolt to unlock it, right? How's that accomplished in a piston driven gun?

Close but no Banana. On a gas impingment system the gas impulse travels through the gas tube to the boltcarrier. When it hits the boltcarrier interior it causes the boltcarrier to travel rearward, thus unlocking the bolt from the lugs on the barrel extension. If you look at a bolt/carrier combo you can see the mechanism work. The bolt rotates about 20 degrees to lock. This rotation is accomplished by the slot in the boltcarrier and the cam pin that resides in said slot.
A piston AR does the exact same thing only instead of gas pressure to the boltcarrier initiating the rearward boltcarrier movement it is now accomplished by a pushrod/piston arraignment. The gas impulse acts upon the piston/pushrod and is contained at the gasblock then vented. This is why the piston AR will stay cleaner and cooler, you are not directing combustion gases to the boltcarrier.

Which is better? They both have their place I guess. If you are the type that doesn't clean your rifle regularly and doesn't mind the extra weight and mechanical complexity of the piston system then there you go.

I prefer the gas impingment system. Simple to maintain, less mechanical mayhem happening when you pull the trigger and face it, parts eliminated cost nothing and can't malfunction. Not to mention the weight savings.
I do have a piston rifle however, reliability proven and simple:
Avtomat Kalishnakova

[Hoosier]

Close but no Banana. On a gas impingment system the gas impulse travels through the gas tube to the boltcarrier. When it hits the boltcarrier interior it causes the boltcarrier to travel rearward, thus unlocking the bolt from the lugs on the barrel extension. If you look at a bolt/carrier combo you can see the mechanism work. The bolt rotates about 20 degrees to lock. This rotation is accomplished by the slot in the boltcarrier and the cam pin that resides in said slot.
A piston AR does the exact same thing only instead of gas pressure to the boltcarrier initiating the rearward boltcarrier movement it is now accomplished by a pushrod/piston arraignment. The gas impulse acts upon the piston/pushrod and is contained at the gasblock then vented. This is why the piston AR will stay cleaner and cooler, you are not directing combustion gases to the boltcarrier.

Which is better? They both have their place I guess. If you are the type that doesn't clean your rifle regularly and doesn't mind the extra weight and mechanical complexity of the piston system then there you go.

I prefer the gas impingment system. Simple to maintain, less mechanical mayhem happening when you pull the trigger and face it, parts eliminated cost nothing and can't malfunction. Not to mention the weight savings.
I do have a piston rifle however, reliability proven and simple:
Avtomat Kalishnakova

So it's just the force of the gas pushing back on the BCG that causes it to unlock, then I can see how both systems works pretty much the same. Why does DI need the gas to actually enter the bolt carrier instead of just acting on the face, like piston?

The other common method for rifles, other than piston or DI, is roller delayed blowback, like the H&K G36, ja?

Thanks for the schooling, and the video is helpful too.

H.

[Not_A_Llama]

Also those failure states related to gas operated rotating block are eliminated, for example if the three washer gaps somehow align.

For what it's worth, I've purposely aligned gasrings before - guns run fine.

Actually... ARs can run kinda crappily with no rings... :-X

[Byte Stryke]

Gas Pistons are simply a different system
as I see it, no better or worse.
yeah, the BCG is cooler and cleaner, but the system now has even MORE moving parts to break in the field, its now heavier.

so I guess its a matter of what you prefer.
not better. not worse.