If Ca is like NJ with gun registration, it's probably easier to have bbls changed than it is to buy a new piece.
I suspect you want to reduce the front end weight of your 629-6. I wanted to do the same thing with my 629-1 since I had an 8 3/8" bbl. I sent it to S&W in Mass and they installed a 6" 629-1 bbl and returned it to me in about a week. The full underlug bbl was available but I didn't want it.
They did nice work.
