New build tight chamber

[sapper]

I've recently put together another .556 ar15. It Headspace's fine. Some rounds chamber tight almost having to mortar them . specifically Prvi. While others chamber fine. I have lapped the chamber with j.b. bore bright. And ran 100 of them through without any issues. But they still chamber tight. How normal is this? Is there anything I can do to help it. Or am I worrying too much and is this normal break in

 

[T755]

What brand of barrel? I also had that problem with that company in 308

 

[sapper]

Red barn armory I have another barrel from them that isn't as tight.
Both barrels have been thoroughly cleaned with a chamber brush And drill.

 

[sapper]

My Mega .308 barrel loves the Prvi 168. Grain match. Sub 1moa all day long. But I haven't been too impressed with the 55 grain .223 Prvi. 3 different ar-15's and the best groups have been 3moa

 

[Drail]

May have been finish reamed with a worn out reamer, or never got finish reamed. Ask the maker. Usually one turn with a finish reamer will open it just enough.

 

[sapper]

I ran another 100 rounds of Prvi through today with no issues becides first round tight chambering. I didn't have to use the forward assist any. Making sure I had a good charge. I watched the bolt for full seating between all shots along with allowing my son to do all the trigger pulling.

 

[sapper]

After cleaning , honing chamber again. and cleaning upper again. I cyled more Prvi ammo through today. It cycled smoother with the round count at 200. And 2 bore honings.
I cycled some reloads from another .223 and they cycled e tremely smooth along with some new steel and some new 62 grain A.E. Opinions are welcome as I am a newbie to reloading and eager to learn

 

[Leo]

Not to be a wise guy, but you do know that JB Bore brite is formulated in a way that you actually are not removing metal, right?

If your rifle is functioning fine now, keep enjoying it. Never use the forward assist, unless you really want to learn how to unstick a jammed round. The forward assist is for pushing through rice paddy slime and the blood and guts that got on the ammo you salvaged out of a fox hole that was visited by a North Vietcong mortar round. It is not designed to resize out of spec ammo.

Sounds like you have a pretty good rifle, keep it clean, shoot it and enjoy it.

 

[sapper]

I wasn't sure. Thank you for the input!! I've been waiting for someone toc chime in with their opinion . no offense taken ibwas hoping that j.b didn't oversize my chamber.