Some (VERY few) Smith revolvers may exceeed 108mm in the "four inch" length, be sure to check (twice) before you accept what's written on the registration if you are looking at one to buy. If the reg is found to be wrong after you buy it, you'll be in serious trouble (I'm assuming you're a law abiding citizen - if you're a gang banger it's not so serious) for possesion of an unregistered prohib. and you won't be able to re-register it since you can't register a 'new' prohib. I've seen one 108mm locally that was cut down in such a way that it is very hard to tell it was cut, but I think it was cut from 8 3/8" as opposed to 6".