My Model 48 is pinned & recessed, has a 1970's s/n but has a internal firing pin. Was this because the 48 was a slow seller? Mine has a 8 3/8" barrel which would be even a slower seller.
No...all S&W .22 rimfires have always had internal firing pins and all even today have recessed cylinder chambers. They also had pinned barrels until about 1981 when all went to the crush fit non-pinned barrels...
Nice gun...had one like it for several years. If you look over on the Ammo board I just posted velocities from an 8 3/8" barrel...