Does the unlimited ammo work on far cry 2 PS3

it actually doesnt work, when you pause the game, and press the first x it brings you back to the game, and when you finish the sequance,you just end up using a grenade and fell like and idiot when you try and try mulitple ways on how to do it, so you make alot of noise then have no bullets when the bad guys hear all your commotion going on