same thing, selecting mp5, my gmod starts crashing

same, its the attachments. certain attachments will cause gmod to crahs, and because attachments save when you drop the weapon, spawning in that weapon will always crash your game. I dont know if the devs really care, they dont seem to be working on the mod anymore but it sucks cuz these are the best guns on the workshop imo

iirc you just need uninstlall some addons
overload of addons (around of 400-1k) leads to bugs on arccw base