Nero:
I've heard all kinds of things about the differences between rimfire and centerfire barrels. I cannot answer the question definitively, but I have read some knowledgeable writers who have suggested that the rimfire barrels are softer than centerfire barrels and so wear more quickly when shot with jacketed bullets. I would expect the rates of twist to differ and a lot of early .22 rimfire barrels seem to be .222 or .223 rather than .224. The early Hornets used a .223 bullet in part because they were being developed on .22 rimfires. I think it was Mark Berenson who was looking for an early BSA Martini that was converted to centerfire and chambered for .22 Hornet as part of the development of that cartridge. Don't know if he ever located the rifle.
Rem
