The key to getting the most out of your avaliable weapon energy lies in two gameplay tips and a simple formula. I won't dwell on the gameplay tips too much as it should be fairly obvious: Spread your barrels out evenly among both of your hands. If you put all your barrels on one side, you're wasting a ton of energy and will have to sit around more often for that energy recharge. Instead if you want two barrels and put one on each hand, you have essentially doubled your energy for free.Second tip is that if you have a weapon that fires slower, tap the mouse button when you fire it instead of holding it down. Holding the button prevents your weapon from recharging, or if you have caps on your gun, will keep depleting energy when you're not firing. Tapping the mouse click at the rate of when the barrels fire will keep your energy levels comfy, and you shooting alien-robot things for much longer. If the fire rate of the barrel is 1 or lower, you will more than likely be able to fire your gun forever by tap firing. It will take some time to get used to, but mastering this skill will eliminate any tension caused by managing energy resources.