The following are known Action Replay Codes for Gun on Nintendo GameCube (GCN).

These codes are for the European version of the game.

Master Code – Must Be On
M5HY-YZ0E-P7BUH
KHWJ-MYWX-2JXCF

Infinite Health
HT2B-PZMV-NQN2J
3W55-T1TC-92K1D

Infinite Ammo
80Z0-9UH4-53Z5D
6GMU-GF06-VG0AY

Infinite Quickdraw
A1ZB-88CU-7ZTER
2EMV-V8G0-C346E

Infinite Money
XEJV-1XX7-C3EGD
FJ6R-QVTY-QCY62

Infinite Drink From Bottle
FGC0-V847-KXTDB
T429-33WK-5UE0P

Infinite Thrown Items
UAGC-W4D6-TG1AX
63H6-Q4FU-2GACX