hnachaj: Not so fast, my friend. Lots of reasons for a round being stuck in the chamber of any shotgun. First of all, was the round fired or unfired? Dirty or clean chamber? Improper shell length in chamber? Worn extractor/ ejector? I do agree that every shotgun needs proper lubrication to work right. I prefer Ballistol.
x2! 870's (that I have known) are very picky about having the correct sized ammo. If it's chambered for "2 3/4 ONLY", then expecting any 3" shell to eject is like expecting to win the lottery.