Gunmetal Cheats

Go to the armory screen just before launching a
mission and press L, L, R, R, click Left Analog-stick, Right Analog-stick. 
ONLY works on missions 1, 3, 6, 8, 9 or 14

At the armoury screen before launching missions 1, 3, 6, 8, 9, or 14, press L(2), R(2), click Left Analog-stick, Right Analog-stick. -From: CoolDudenum1@aol.com

Enter this at the mission select screen:

LTHUMBSTICK BUTTON, BLACK, R, RTHUMBSTICK BUTTON, WHITE, L

While playing, press Left Analog-stick, White, White, Back, Right Analog-stick, White.

Use Hybrid control for easier control. This may seem awkward at first if you're used to using the 'Classic' control scheme. Trust me I went from Classic to Hybrid. This really helps. The controls for the Gunmetal Mech is the same. The Jet controls are different though. This is easier because the brake and thrust is the Left and Right Triggers. So you don't have to take your finger off of the Right Stick (Classic Mode) to press barrel roll (B button in Classic Mode). Try to practice with Hybrid Controls and play through beginning of the levels to the current level your at till you finally feel comfortable. (This makes dodging rockets easier and also the Right Stick on Hybrid is a quick weapon select which is very handy so you won't have to press A constantly if you use Classic Controls