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czwicky 03-01-2012 10:01 PM

Short barrel AR
I was thinking the other day about sawed off shotguns and wondered if the same principal would work with an ar-15. Rethreading the end of the barrel in 1/2x28 wouldnt be a problem, but would this be possible/have any negative effects on the rifle except decreased accuracy? Thanks for all responses

pagj17 03-01-2012 10:07 PM

It would need to be re crowned. If it's chrome lined, it would encourage flaking of the chrome( from my understanding, theoretically impossible, but particularily with FALs it was shown to happen).
Depending on how short you cut it you would need to either widen or re-drill the gas port.

czwicky 03-01-2012 10:25 PM

Rr-crowned? And i dont plan on cutting it past the gas block. I want an inch between the block and the end of the barrel so i have enough room for my piston drive system and a suppresor

JonM 03-01-2012 10:55 PM

if its cut less than 16" from the bolt face to the end of the muzzle, NOT the flashider, and you havent registered it as a SBR or its not on a registered machine gun you get a free ride to prison for 10 years.

the crown is the area around the muzzle where the bullet comes out. if its not concentric the bullet can tumble or fly off in random directions. just chopping it off with a bandsaw or hacksaw is a good way to cause serious injury or death to innocent bystanders if you dont know what your doing.

changing the length of the barrel changes the gas pressure exerted on the piston shortening the barrel without moving the gas block reduces the pressure and can easily cause extreme fail to feed turning your semi auto into a bolt action.

it doesnt take much shortning to affect the cyclic function.

AgentTikki 03-01-2012 11:28 PM

WELL NOW if he pinned and welded his supressor, then the added length of the suppressor will help him make his rifle at least 16" long. (do you really wanna do this?) Then you wouldn't have to do all time and paperwork for SBR'ing your AR.

I'd be concerned about timing when doing this. (like what Jon said) There's a lot of issues (including redoing a crown(like what Jon said)) that you'll run into.


A switchblock would only be useful if you were able to remove your supressor.

A JP adjustable gas block would work better for this situation.

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