[MERGED PR] Prevent RPG ammo in the zip gun

[Carbadox]

I thought using RPG ammo in a zip gun would already give it a high chance to explode
Also considering this would only affect nuke rounds I don't see the point in this PR. This would only harm the crew from stealing RPG rounds from the syndies and using it on them.

That's kind of a silly thing to say. Only the Nukies have the foresight to know what mode it is and how to prepare. Even more so that they're the only ones that can consistently utilise the RPG rounds