Did a 23cal a long time ago. (97/98?) It was a way oversized 22cal barrel hand lapped out to 23. It took forever to do. JM made dies to make 30cal pellets for his old RWS52 30/30 conversion. It was a jig that would mash 25cal pellets down and flare them out to 30cal. I pretty much did the same thing he did to make the pellets. Jim made a 21cal recently. It's on his gallery #3. I don't have the spare time like I did back then
Paul