They're all pretty much 12 ft/lbs unless you whack in a heavier piston and open the transfer port about 0.3 millimetres. All that bollocks about stronger springs is shite, doesn't make any fucking difference.
just spend £400 on a Legal limit weirauch, which will easily kill rabbits at 30 yards, and if that's not enough, apply for a F.A.C and have the police up your arse every 6 months until you relinquish it.