I didnt see the smokeless sub forum so I guess it got nixed. Anyway I had a h&r 4570 converted by someone off of Doug's message board back in 2014 so 8 years ago. I can not remember which breech plug he used. It has a tungsten core bushing in the center and a Allen set screen on the outside to hold the bushing in. I am not having any trouble out of it but thought I'd go ahead and replace the bushing before season gets here. Problem is, I can't get the bushing out and I don't know where to get one. Any info?