All of the specs for a barrel seem to be the same as that for the .32 S&W long, short, etc. The twist that ruger lists for their pistol is a 16"rh. with 6 grooves .312 should be the groove diameter and the bore should vary depending on whether it was going to shoot cast or jacketed bullets. Walther has a .305 bore for the 32 target guns with a 17 twist.

Tom