Perhaps you have never seen a combat weapon. A truck gun will not get nearly as dirty as one a soldier is carrying and beating the crap out of.
Hardly opinion, look it up. Most guns produced have a thing called a serial number and the armorers keep logs on these weapons, especially those use by force recon and the like.
Once again, if you have seen weapons that have been used for decades and been through combat and training you will notice they are beat to crap. Metal holds up a bit better than plastic.
You need to do some research.
This post was edited on 2/19 at 10:59 am