A bolt body out of a 110 action wont fit on this shotgun, incase that is what you are thinking. The shotgun bolt is fatter.

Mine just loves the Federal 3" Barnes expander slugs. It hated the 2-3/4 Accutips.

As for the trigger, I didnt check the pull weight on mine to see if it would go down to 2.5 or not(and Im fine if it is 3.5lb), but it is ALOT better than the 7-8lb trigger on my old 870 remmy.

If your POI is moving back and forth like that then something is loose. Is the scope brand new or did you have it on another gun? I would try another one since you have a spare just to prove it good or bad.