Anyway to loosen (ream out) a .223 Chrome Lined Chamber??

I have an older Model1 Sales barrel (14.5") that I have been using in full-auto but the chamber is .223 and not 5.56 ( Not sure how I screwed that one up). Most, if not all, of the ammo I fire is 5.56. So far it has been 100% reliable but I have not really shot more than 2-300 rounds at a time. I know the looser chambers are better for full-auto and can be a benefit for when a chamber gets dirty. I also noticed the casings do not seem to eject as far as my uppers in 5.56. Thats what got me thinking that maybe the chamber tightness could be an issue if it got too dirty.

Any solutions or should I leave it as is?

ASO544

I think once it's chrome-lined, it's pretty much set in stone.

WIZZO

Chrome can be stripped. Then you could ream the chamber. Then have it chromed again.

It would probably be easier and maybe cheaper to just buy a new barrel if you can't use this one as is.

If it was me, I would buy a new barrel.  Find a used one from the EE.

A carbide reamer will cut through the chrome.  It may affect the reamer life somewhat, but it will cut it.  You'd have a distinct cutoff leading to the chrome lined bore and I understand that the extreme conditions in the throat area will start stripping the chrome in the bore as well.