In 40k tabletop boltguns have no AP. That might have changed in the new edition but yeah, boltguns just explode so deal more damage.
Hotshot is hyper focused with shorter range and higher power draw, not that wrath really deals with ammo very well, so it makes sense to me. Though I'd argue bolters should have at least 1 AP due to their caliber but yeah, only the stupid primaris bolters do in wrath.