In gears 3 you're able to swap weapons with your AI/human team mates. The great thing about this is that after using up all their ammo, if you hand it back to the same person and wait for them to fire that weapon you took off them. This resets the weapons own ammo counter. If you now ask for the same weapon back again, you'll notice that the ammo has been replenished for you! Repeat this as often as you like, giving you effectively infinite ammo! Credz to Keysnsamples