PDA

View Full Version : same old AR questions... piston retrofit??


jborushko
December 25, 2010, 05:06 AM
i know im probably betting a dead horse here but here goes.

i like to tinker with stuff and while i dont feel that a piston operated ar15 is any better than the gas impingement system, i would like to try it out none the less.

what i gather is that the 'long stroke' is better than the 'short stroke'

the question... any suggestions on what i should try? best for the money (i dont want to spend more than $350)

what have you tried? what do you suggest?



i've been told Black Hole weaponry, which is local to me (Washington) but due to the season i didn't want to call till January to get the scoop from them

also Atlantic firearms makes one less than $300

jborushko
December 25, 2010, 06:05 AM
sorry for the double thread post... my computer locked up and i refreshed the browser. mods delete one of these if necessary please

Ridge_Runner_5
December 25, 2010, 04:49 PM
For your price range, I'd recommend the Adams Arms retrofit kit (http://www.adamsarms.net/details.asp?sku=CPS-D-ADA). Comes with a railed gas block, piston and I think a replacement one piece bolt carrier.

SR420
December 25, 2010, 08:19 PM
Don't do it. You are better off with the DI as is or a rifle that's
designed and built to be a piston driven gun from the get go.

MMcfpd
December 25, 2010, 11:35 PM
Don't do it. You are better off with the DI as is or a rifle that's
designed and built to be a piston driven gun from the get go.

He said he likes to tinker and wants to try it out for himself.

Over on arfcom's EE there are Ares retrofit kits (http://www.ar15.com/forums/topic.html?b=7&f=22&t=802863&light=) (which are what Bushmaster sells as their retrofit kit) for sale for $199.95. I have no experience with them.

SR420
December 26, 2010, 09:11 AM
Well then, I hope he likes to tinker with Carrier tilt.



The biggest overall problem with Piston AR's is Carrier tilt.

Why is there tilt? There is tilt because Gas Piston AR's (GP-AR's) do not have a carrier key that is a gas tube like on DI-AR's (regular AR, Direct Impingement AR's). The carrier key of a GP-AR is a solid so the piston has something to strike to move the BCG (Bolt Carrier Group). Since the piston is striking the BCG from the top and off axis (off-center), it causes the BCG to enter the buffer tube at a downward angle. DI-AR's does not have carrier tilt because as the gas enters the bolt carrier key, it is bled off and the BCG enter's the buffer tube straight in. GP-AR's piston action strikes the carrier like a hammer, therefore causing tilt.

jborushko
December 26, 2010, 09:34 AM
anybody try the firearm ready solution anti tilt buffer?

possible solution to the tilt?

http://www.youtube.com/watch?v=Q94E55-TkKU&feature=related

seems to me a very solid idea!

SR420
December 26, 2010, 09:49 AM
That's a solution to a problem caused by a solution to a problem that doesn't exist ;)

It's your time and money - go for it and let us know how it works out.

jborushko
December 26, 2010, 10:16 AM
That's a solution to a problem caused by a solution to a problem that doesn't exist

thats the same kinda reasoning that would have us all still trowing rocks and our food to kill it ;)

just like any new system there are growing pains and further research... just look at the original design of the AR15 to what it is today... forward assist better sights ect. would it be better in your mind if this buffer design came out WITH these new piston kits?

i like trying new things sometimes, though like many others i keep my feet buried in the sands of the old designs in many regards and especially with my guns. though some things i like to play with. dont worry when i do get around to do this mod i will let everyone know.


now any other suggestions on kits that you guys have tried?

demigod
December 26, 2010, 10:18 AM
The better conversion kit would be to retrofit a PISTON gun to Direct gas. Piston DOES NOT WORK over the long haul on the AR platform and is a solution to problems made up by piston salesmen.

jborushko
December 26, 2010, 10:22 AM
can you show me an example of "not working over the long haul"?

any personal experience of friends experience you can relate?

garmar45
December 26, 2010, 02:38 PM
Kinda off the mark here, but does anybody know what the CMMG platform runs - DI or piston?
Thanks

Ridge_Runner_5
December 26, 2010, 02:52 PM
CMMG guns are DI.

All AR-15s are usually DI unless it says piston in the advert. Except pistol calibers models, those are blowback like a handgun.

MMcfpd
December 26, 2010, 03:34 PM
Except pistol calibers models, those are blowback like a handgun.

For the most part that's correct, but there are DI pistol caliber uppers: Bazooka Brothers RMW .45ACP DI upper (http://bazookabrothers.com/products2.htm).

Volucris
December 26, 2010, 05:47 PM
From my studies there are no good piston conversions for AR15s. You're much better off buying a rifle designed for a piston to begin with.

If you already have a DI-based AR15, I strongly suggest looking into a Sig 556 from CDNN sports for under $1k.

tirod
December 26, 2010, 05:52 PM
Another way to look at blowback is it's really Direct Impingement. The gas in the barrel forces the case out of the chamber. Unless you consider the brass a piston, in which case the AR bolt with gas rings is, too. The bolt carrier is the gas cylinder, which is propelled backward hard enough to cycle the action.

Spending $300 to add a piston kit on the barrel also means disabling the piston kit designed into the bolt. Net result, $300 in the hole, action still cycles, nothing has really changed.

Which is exactly why piston kits on AR's seem so futile.

If tinkering is the goal, then ok, tinker. Don't expect to discover anything, the whole point of the AR was a move to dump the weight and complexity of a piston system to begin with. It does, what some have against it is based on word of mouth misinformation and myth.