How do i get the infinite ammo wig? any help is much appreciated

You have to collect all the dog tags in the entire game. I know, pain in the ass...

Actually not all of them. You have to collect around 100 or more to get it.

Information I got was from GameFAQs. Looks like they should update.

If you can't be bothered remembering, Just just play the game 3 times, Very easy, easy and normal. Collecting Tags from every dogtag you see.