i just got a used remington 870 exp mag 12 ga. it is in pretty nice shape even the action is very clean no were marks on it except very slight marks on the mag tube. the only thing is the inside of the barrel is almost black. shines no pits just black. my first shotgun. this normal or needs a good cleaning the code on barrel is OO think thats a 1977 ? the choke has a scratch or two. i dont think that will hurt any thing will it ? could i use steel shot in this barrel ? doubt if i will ever use it but good to know.