Yes, it is a four incher.
I used the trigger lock one time out of curiosity. It resembles a small "skeleton key", looks pretty generic. I'll never use it again. No need.
Recoil is noticable, but more of a push than a smack. One of the joys of a 45 acp revolver is, it will shoot anything. As long as there is enough velcocity to send the bullet downrange, it works in these guns. Full power loads are no problem either.