Piats are really good. They have 80 deflection damage and 120 pen damage. Just only use ATTACK GROUND (std hotkey G) Dont let them "auto shoot" Dont forget to make a nice blob to one shot a KT/ tigers etc.
PIAT's even with attack ground suck ass with their accuracy, at max range even hitting a bunker is problematic let alone a Luch
pretty much just a gimmick weapon to blob vs a unsupported tiger and nothing else. One MG42 will shut that down