Been gone from the forum awhile, good to be back!

I have a Stevens .223 with a heavy Varmint barrel on it. I bought this from Gander Mountain that someone traded in over a year ago.
I started a thread on here awhile back but cannot find it.

This is what Savage has for this gun:
MOD 200XP 223 REM VARMINT BLK OX - Manufactured: 06/04/2009

I could not get it on paper when I bought it (about 4ft to the left and 3ft low) so I took the barrel off and put a 300 black out on it for a while.
In the interim I did a chamber cast and it appeared to be right on spec.

I just could not give up on it so I re-installed it back on its original action and just got back from the range and again it was off the paper but this time it was 3 ft. high. I have tried 3 or 4 different scopes on it also. You site down the bore and see the red dot on the paper and look up at the scope and it was only about an inch off elevation and windage was dead on!

I guess my question is instead of using this barrel for a tomato steak, what could/would it be able to re-chamber in without spending the same amount for a new rifle?