I had the same issue with a TC muzzle loader. I put a Nikon I took off another rifle (no issues there) and put it on the TC. No good. Take it to gunsmith who said tap holes off. I had 2 other scopes on it with no problems. I talked to TC and they say send it in. I listened to all gunsmith reasonings and took it home and ordered the Burris Signature Rings with inserts. Put it on my self and DONE.