thinking of upgrading

[car-15]

to a gas piston setup anyone here have opinions pro or con? link below to the one i'm thinking on ordering.
http://www.bushmaster.com/shopping/uppers/pre-ban/bura3b16m4-gp.asp

[HunterCO]

Talk to Alan he has a gas piston M16 It runs great.

[Great-Kazoo]

Talk to Alan he has a gas piston M16 It runs great.

i thought he had it listed in the for sale forum .

for the money bushmaster wants i'd look at the ARES kit. $300 ish AND if you decide to sell you upper. it is an easy uninstall, w/out having done any damage to your upper.

[David121582]

If you actually look at ares' site it says $199. Make sure you ask for mil discount if it applies to you they give 15% off. I plan on ordering mine in the next week or two.
Dave

[Scanker19]

If you actually look at ares' site it says $199. Make sure you ask for mil discount if it applies to you they give 15% off. I plan on ordering mine in the next week or two.
Dave

What's this web address you speak of?

[David121582]

http://aresdefense.com/

[theGinsue]

If you actually look at ares' site it says $199. Make sure you ask for mil discount if it applies to you they give 15% off. I plan on ordering mine in the next week or two.
Dave

The price that was quoted in the post just before this post of yours was 4 years old. When you resurrect a thread, keep in mind the age of the comments you're addressing.

[car-15]

The price that was quoted in the post just before this post of yours was 4 years old. When you resurrect a thread, keep in mind the age of the comments you're addressing.
+1, and I got a sig 556 instead of converting btw[Tooth]

[David121582]

lol sorry I just looked at the month/day and assumed it was recent.

[Byte Stryke]

http://web.me.com/jallegri/webpix/zombie-thread.png

[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.
:D

[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...

M7GTZ0DixqA

[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.

[BPTactical]

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.

As far as the gas entering the carrier it acts as an expansion chamber, allowing chamber pressure to drop to a safe level before unlocking the bolt. It also is doing the same thing as a piston, hence the gas rings on the bolt. You have to contain the gas somehow, otherwise the pressure drop will not cycle the action.
With a piston rifle this "buffering" is accomplished by venting a certain amount of gas off before the piston.

You also have weapons systems that operate purely off of recoil, the 1919 and M2 come to mind.

[Not_A_Llama]

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?
H.

BPTactical covered it, but another angle on DI: The force generated by the gas acting on the piston face of the bolt is linear, acting to push the bolt assembly backwards. It's the cam pin that creates the rotation necessary to unlock the bolt. The reason the gas goes into the carrier itself is so that the pressure can act against the larger surface of the bolt, and so that the gasses can be vented outside the rifle when the bolt has reached its full extension.

[BPTactical]

BPTactical covered it, but another angle on DI: The force generated by the gas acting on the piston face of the bolt is linear, acting to push the bolt assembly backwards. It's the cam pin that creates the rotation necessary to unlock the bolt. The reason the gas goes into the carrier itself is so that the pressure can act against the larger surface of the bolt, and so that the gasses can be vented outside the rifle when the bolt has reached its full extension.

You bring up a good point Llama-linear force/ bolt carrier tilt on piston AR's. Linear force applied by gas is applied equally, meaning you get an "even push" straight back on the boltcarrier meaning the carrier is coming back in a strictly linear fashion.
With a piston AR that recoiling force is concentrated in one area, the top of the boltcarrier where the gas key is usually located. That causes the boltcarrier to "tilt" somewhat and if pronounced enough, binding or shortstroking of the boltcarrier can result. In extreme cases the buffer tube can be deformed/gouged by the carrier. This is where using only Mil-spec and top quality components should be utilized if converting to a piston rig.
Upper end conversion boltcarriers will have "skids" built in to the bottom rear of the boltcarrier to "minimize" carrier tilt.
Another case of reinventing the wheel when it really isn't needed. You create a new set of problems when running a piston system in a firearm that was not originally designed for it.
Beware of conversions that have you replace the gaskey with a solid faced key for the pushrod to bear on. You WILL shear the gaskey screws.