"With Liberty and Justice for all" "You shall receive power" Acts 1:8 "My word does not return void, it will accomplish what I wanted" Isiah 55:11 United Air Epic Fail Video https://www.youtube.com/watch?v=u99Q7pNAjvg
It works if you cycle it manually? If the bolt is not going into battery, there is something in the mechanism or the locking recess of the barrel. I have a 9200 which is very similar and found that the gas system parts can be assembled in different sequences. There could be a rough place on the mag tube near the front.
Had a Beretta 390 that wouldn't fully close in cold weather. The official answer was don't use RemOil in cold weather. A Teflon lube like Break Free. I thought it a bunch of hooey, but sprayed it with Break Free, no more problem. RemOil was just thick enough to slow the action. Others have good points
Do you have a 2-3/4" or 3" chamber???.. IIRC the "magnum" barrel is marked " for 2-3/4 and 3" magnum shells" The 2-3/4" shells mean high bras magnum 2-3/4"....Not the Wally World dove loads.... Check the writing on the barrel... Mossberg makes a 5500 barrel that is for low brass only.... JIM..............