I'm curious as to just how short a standard 20 barreled version AR can be cut without having reliability problems.

We all know the Bushy dissapator uses a gas block in the shorty position with a front sight base mounted where a normal 20" barrel FSB would be. This would seem to indicate that I can't go 16" without some sort of problems, otherwise Bushmaster would just chop the barrel and not worry about anything else.

So..just how short can you go and have sufficient gas pressure the action reliably?

Good Shooting
Red

I've seen guys cut them to 18inches.

Any shorter and you might have to open the gas port or add a Krinkov gas moderator/FH and that would add length anyway so I reccommend 18inches.

I don't like the BM dissipator because in my opinion it should have a mid-length tube like Les BAer's and I don't want to buy the expensive Les Baer product.  

But then again with my ACOG I'm stuck with 14.5inch anyway.

I agree with Greeno, but there is still no guarantee that at 18" you still won't have to open the gas port. It all depends on the type of ammo and how finicky your AR is.

It's no problem to open the gas port a hair. Whoever cuts and crowns your barrel should be able to do it. But is it worth the cost and aggravation for 2" less?

Lee
[url]www.thearmsroom.com[/url]

Well, I'll let you know how it works as soon as it gets here.  I'm waiting for a new 16" A2 profiled DPMS barrel that started life as a standard 20" A2.  It is shortened to 16" length but used the same long gas system.  My guess is that it should work fine since DPMS is building "dissipator" style carbines with these (except full heavy barrel contour.)

I would just go with a 16" Kurtzgewehr
with full length gas tube have kurt open up the gas port...he's been doing this successfully for a quite a while..

I believe the millitary found that you needed 4.5 inches ahead of the gas port.  But I don't recall where I read it.