RE: Remington 870 Barrells??
Somewhere in the past Rem changed the bbls. What they did was where the mag cap has a detent ball, the new ones actually use the mag spring holder thingy to hold the mag cap tight. Dunno if you understood that, but some bbls will and some wont. Rem did that so you would have to buy a new gun if you wanted certain bbls. Its all about the money!