if you dont use round drum on thompson, i wouldnt use it at all cause it runs out of ammo pretty quickly.
but of course the Mp40 is a bomb gun so i have to go Mp40
double tap is lame though, i understand your asking between double tap for the MP40 and Stopping power for the Tommy gun, but seriously, double tap is whack. ALl it does is burn ammo and gives you added recoil.
Roll with stopping power or jugg. MP40 by the way. Tommy Gun is pretty much just as good though if you got the drum.
ya double tap on mp30=crazy recoil, i like the mp40 with jugr or stopping power but im always switching with the smgs. i use them all but mp40 is da best out of em.