I was going to bring that up, but the cost of entry into reloading is probably prohibitive in this case.Circumstances like this are why people invest in reloading tools. You could make your own low-pressure loads.
Your 1100 should eject trap loads just fine. Check the O-Ring that fits over the magazine tube. (If you remove the forend you should be able to see it). It's common for them to dry out and crack, or split........ I did some trap shooting with my Rem 1100 semi auto years ago. With that, trap loads wouldn't allow but single shot while hunting loads would operate the action.