Are they still using the "floating chamber?"
IIRC, designed by Carbine Williams.
My 1962 model was a chore to reliably switch between ammo types.
It required very frequent chamber cleaning.
I have a 572 field master model that I would not sell for double its retail.
Very under appreciated design and ergonomics. Points like a 20ga framed shotgun.
The 20ga 870 wing master buttstock will fit the 572 model with no fitting required. Nice swap if you bought one with the check riser monte carlo type stock and wish to use the wonderful iron sights rather than optics.
The lower cheek weld allowed by the shotgun stock really makes the irons line up like a lazer.