[MERGED PR] Prevent RPG ammo in the zip gun

[Trustworthy]

Just remove the zip guns ability to load any ammo entirely imo, I'd rather we have different makeshift weapons for different ammo types than one that does it all, and leads to stuff like this, where people load RPG rockets, or OHR rounds into a zipgun and get a basically free instant kill on anyone at the cost of a limb and maybe a stun. Though I understand that such a drastic change is best not done all in one go, so for now, I'm content with this.