Infinite ammunition

Get over 300 medal points, then press Start and enter the "Rewards" menu. Choose the
"Weapon Select" option and pick from the available weapons. You will get a weapon with
full ammunition. Then, re-enter that menu and repeatedly select and deselect that weapon
to keep refilling its ammunition.

this is a easy game how can i chase it to god mode?but it is really hard level 21
confrontatie that boss and the zombys