Model 53 22 Magnum
The 53 bore is .222 like 22 L.R. The Model 48 Bore is .224. The Model 53 is 22 Center Fire Magnum, The Model 48 is 22 Rimfire Magnum. The Model 53 was never chambered for 22 Rimfire Magnum with inserts or aux cylinder. If you reload for a 53, you should never load bullets...