The 63 S came to be in order to get the last bit of useful life from a throat-eroaded barrel. You could seat the bullet close to the lands and still have some shank in the case neck.(220 Swift et.all, shooters note) When deer hunting with 22s was a new idea, the 63 S was the natural choice. I shoot 55 S SMPs as a first choice in a pasture poodle gun, accuracy is to brag about...Bill
