Even if rifle barrel break-in were necessary, handguns are a whole 'nother beast. The inherent accuracy, more correctly the inherent lack of accuracy, far over-shadows any benefit that might theoretically be available from a break-in. Imagine if you gained 1/2MOA at 100 yards (just for arguments sake), you'd be getting 1/8 MOA at 25 yards, which would be 1/32".
Besides which, a few (careful) minutes with a bore mop and some polishing compound would clean up any pistol barrel to a mirror finish. Much easier than with a rifle.
Still happily answering to the call-sign Peetza.
You do not HAVE a soul. You ARE a soul. You HAVE a body.
He is no fool who gives what he can not keep to gain what he can not lose.
-Jim Eliott, paraphrasing Philip Henry.