Even when polished to a mirror, the Winchester "Super Target" 12ga 2-3/4 1-1/8oz #8s 100-pack ('Silver' brass)
will
not go back into the barrel once fired.
Again, see
http://thefiringline.com/forums/show...7&postcount=25
The 870's chamber may be 10% of the problems, but the steel-based shells now being sold as "bargain" are all the rest.
(When a bargain is just too good to be true -- depend on it being just that....)