I agree with the cryo suggestion.

I know two guys that did it with their shotguns and it really helped.

Also just check to see if the barrel hits the stock. (floating) I had a 7mm that was throwing bullets also. When the barrel was floated (buy me with a dremill tool and yes it was a "hack job" but I digress) It then shot very well. It seemed to throw them on shots 4 & 5 for me.