The brls marked 2.75-3" The receiver is not marked for length. This is a factory setup.
Almost all 870 barrels are marked that way. Problem is, the receiver could be an Express (2 3/4" only), Express Magnum (2 3/4" or 3") or Express Super Magnum (2 3/4", 3" or 3 1/2"). The barrels will interchange on all receivers, so it's not what it says on the barrel that you need to look at.
I took the 870 out this morning and shot some different slugs thru for brush hunting next week.
Its an 18.5" brl'd 2.75-3" 870... the 2.75" cycled fine, but the 3" I had problems with the hulls jamming in the ejection port... anyone else have this problem?
Make sure that your not easing the slide rearward when you extract a spent round from the chamber. I've seen the problem that you describe happen when the shooter doesn't pump the slide back hard enough. The 2 3/4" shells clear OK but the 3" sometimes hang up.
All that is necessary for the triumph of evil is that good men do nothing. Edmund Burke