What Remi told you is total B.S. Iv'e changed bbls on 870,1100's and 1187's. never had a problem with them. Only once on a older 870 Wing master , when i changed the 28" full to the skeet bbl, it was a tight fit. But it worked fine. Do like the other member's said, get the part's you need from some body that know's what there talking about.