I have made a 22LR center-fire cartridge from 25 auto cases. Cut the rim and web down and then swage the case in three steps to the same size as a 22 LR. I did it to see if it could be done during the scarcity of the rim fire ammo. They work well and with 0.9 grains of HP-38 they have right at 1180 fps from my 10" Contender. That is the only gun that has a center fire firing pin and a 22 LR barrel. Reloading them is cheap but I had to swage my own bullets because the cases are thicker than a standard 22 case. The cases and bullets are .226" diameter which is just a thou over the average standard for 22 RF ammo. It fits well in standard chambers and no leading to speak of with dead soft lead.
