Most of the time it will work.
The older 1100 barrels used a thinner ejector, so you may have to open up the slot in the 1100 barrel for clearance.
The groove for the O-ring are in slightly different positions. Most of the time it makes no difference. Sometimes two O-rings will make it work. Sometimes they just don't work. I suspect tolerance stacking is the culprit.
Short answer, I would not buy a barrel expecting it will work, but if I had access to a barrel I would try it.
Michael