no offense, but mossbergs don't pattern that well at all from wat i see at the patterning range. it depends on wat kind of squirrels and the range then i could tell u something.
I shootem with a 22 LR. and an 870 12 gauge 7 1/2 shot. I have a 17HMR and it tears them apart, I wish I had a mach 2 though.. Cant wait till it opens..