There is a pivot boss on each side of the receiver on which the barrels pivot....they are not thru bolt hinge pins.......on the inside they look like large round pivot pins......
(
mechanical definition: - boss/bas/bos..3a.: the enlarged part of a shaft on which a wheel is mounted..b.: the hub of a propeller)
These two pictures are S-685 Beretta's..circa 1982.....
S series Beretta's have chrome lined bores and steel could possibly destroy the nice chrome bores......?......
I have shot lots of buck shot and slugs through mine with no ill effect whatsoever, but that was lead of course......
Hope this helps.....
