Was given a 20" bbl today with a muzzle brake on it. The previous owner was trying to remove the muzzle break with dremel foo and a file, and kinda fubared it up.

He enlisted in the Army, and didn't want to deal with it, so he gave it to me. I know a guy I with a lathe, so I can cut it to 18" and rethread/recrown to get past the butchering

But what about the gas port?

What size would be best for an 18" bbl?

Mine required opening up about .010" to keep the same ejection pattern.

It probably would have run on the same port, I've heard of guys with that experience, but I liked having it run right.

Open it up to 0.108 of an inch.