it IS possible to kill Verdugo with shotgun/Striker blasts.
Once, i used up all of the nitro tanks and i thought my Striker wouldnt be able to kill him, but i kept shooting him with the Striker and eventually his exoskeleton cracked.
On my riotgun handicap run, i was able to shatter him while frozen using the very last nitro tank.
hitting him while he's frozen will just triple your attack damage. and he has 900 hit points.