Win.1901 won't feed from magazine.HELP

YEP,it will not feed from the magazine into the chamber.It function fine until you go to close the bolt,then the bolt,for some reason,over-rides the back of the cartridge and jams it up.Other wise the back of the shell ends up under the bolt.I have been using all brass shells.I should try it with modern shells.Is it possible that the rims on the all brass are smaller than new plastics?????ust writing about this problem helps.Thanks for any and all attempts at help.Bill

BILL
KEEP YOUR POWDER DRY.BUT NOT HOT.....