Pooch,

The early 50s SO series guns have a 7 pin lock along with a cocking indicator. Beretta reduced the complexity on the locks in '58 or '59. Nothing wrong with the 7 pin locks, but if they go wrong they are just harder to repair. The guns will be around 7+ pounds. The earlier guns will also have a solid rib; the later guns will have a vent rib. I don't see many early guns with a SST however, you can find DT guns.

I used to hunt with a mid-50s S3, but now hunt with a side-by-side. You should be able to find a good early SO series gun.

Ken