Could be the ammo too. What kind you using - steel or brass primer? My 870 wasn't too fond of the cheap steel primer garbage. Win AA's it'd fire all day long w/no jams. Maybe 1 or 2 outta 50 cheapo's tho would jam. Expansion of the primer lodged it pretty good in the barrel. I Know the 1187 isn't a pump like the 870, but ya may wanna try chaning up your ammo before you go replacing parts. Helluva lot cheaper fix.