Contra III/Game Mechanics and Glitches

Fast Weapon Switching

Contra III lets you carry a weapon on each hand. Most of the weapons in Contra III have a "cool down" time. For example with the crush gun you can fire three shots at a time and one of the shots has to disperse before the gun can fire again. If you have a crush gun on both hands, you can press the X button to switch to the crush gun on your other hand and fire three more shots while you wait for the cool down on the first three shots. Contra III has auto fire when you hold down the Y button. By holding Y and rapidly pressing X you can quickly switch between both weapons. You can do more damage with almost every combination of weapons using this technique.
Maximizing damage with the crush gun
The crush gun is the most powerful gun in the game, however it does so by creating explosions that disperse randomly. To ensure that you are doing maximum damage with this gun, you need to get as close as possible to your target without dying. Make sure you hold Y and press X as rapidly as possible to ensure that you are always firing missiles as rapidly as you can.
Note: When you have the crush gun on each hands, you may want to only fire all of your missiles in some areas of the game to avoid creating too much lag.
Maximizing damage with the peashooter Yes, even the peashooter benefits from fast weapon switching in some stages. You do not do double damage by pressing X rapidly with the peashooter, you only do slightly more damage. The peashooter does not benefit from fast weapon switching in the top view stages 2 and 5.
Technique for holding the controller When you hold the controller you need to rest it against something. Hold down the Y button with the index finger and twitch your middle finger.