Hatfield sas questions

I have a 870 clone that holds 4+1 2 3/4" shells but only 3+1 with 3" hi brass shells, maybe yours is the same.

Yes it makes a difference on what length shells you are using. Most shotguns will hold 1 less when using 3" shells. Mossberg 500 shotguns are all advertised as 5+1 no matter what the gauge is. If you use 2 3/4" or 2 1/2" in 410, then they will hold 5 shells in the tube. Go with 3" shells and they will only hold 4. My 870 is the same way.