Are the through holes in the chamber or the receiver ring? The receiver ring is where the lock lug reside. It is ok to have through holes in the receiver ring, but in the chamber only blind holes can be drilled. Through holes in the chamber mostly means your barrel is done for. When fired, the brass will flow into that hole. If you are lucky, you will have stuck case. Worse the case will blow out as there is no steel support where the holes are. Plugging the holes is not recommendable. If the plug fails, it becomes projectile. Be careful.