Sounds like you are dealing with an off center QLA, or as @Grenadier1758 suggested, some sharp edges.
Or you go right into sharp edge/burr removal. To this I would suggest cleaning the bore with something like Scoth-Brite. It won’t hurt anything and stands a good chance of helping to remove any sharp edges or burrs where the QLA counterbore and the bore meet. Mike Bellevue (@duelist1954) has a good video out showing his version of the process. I have used a similar method for some time, but Mike explains his very well. I started doing it after speaking to Don Getz (Getz Barrel) years ago before he passed, and he recommended using the green (600 grit) Scotch-Brite for smoothing up barrels that were cutting patches. Said it wouldn’t hurt the bore.
Unless you have access to a lathe to bore out or cut off the QLA, I would suggest trying to clean up the sharp edges first. If you have a borescope, time to take a look. A way to check for patch damage at the muzzle is to drop a short piece of brass rod (maybe 6”-12” long, 3/8” diameter for example) down the bore BEFORE loading a patched round ball and pushing ball a few inches down the bore. Then by rotating the barrel from muzzle up to muzzle down the brass rod works like a slide hammer to push the patch ball out so you can examine the patch.
Or you go right into sharp edge/burr removal. To this I would suggest cleaning the bore with something like Scoth-Brite. It won’t hurt anything and stands a good chance of helping to remove any sharp edges or burrs where the QLA counterbore and the bore meet. Mike Bellevue (@duelist1954) has a good video out showing his version of the process. I have used a similar method for some time, but Mike explains his very well. I started doing it after speaking to Don Getz (Getz Barrel) years ago before he passed, and he recommended using the green (600 grit) Scotch-Brite for smoothing up barrels that were cutting patches. Said it wouldn’t hurt the bore.
