there are weapon mods for like, mercury and nitrogen and stuff. I just want to know what weapon they actually go for, and if they are for the obvious weapon that you think you can put the ammo converter for say nitrogen into, then how do you get them in. I tried to use the mod, it all seemed to be labeled properly to go for the gun I was trying to put it into, but it wouldn't go. So i'm looking for a how and what. how do you get it into the weapon. what weapon is it really supposed to be for.