[T Smith]

My 2 kids and myself all purchased ICS M4 rifles a couple weeks ago. Two of them were purchased locally. I upgraded 2 of them with an ICS M120 spring, Guarder shims and metal bushing. Rather inexpensive upgrade. Total cost about US$30. Mine is consisitently shooting 429FPS and my younger son's is shooting 400FPS. Now here is the odd part. My older son wanted his professionally upgraded and got his from RedWolf. What a big mistake! Cost about US$225 more getting his gun from RedWolf. The upgrade was a "Level 4" and suppose to shoot 450FPS. We checked the speed and it was only shooting 370FPS!!! The upgrade included Systema Directional Piston Head, Deep Fire Titanium Piston, Systema gears, Prometheus spring, etc. I thought they probably put in a stock spring in error so I replaced it with a Systema M140. Still only 370FPS. I also noticed there was almost zero lube on the gears and none on the spring upper assembley. Really a sloppy upgrade. I lubed everything up properly and no difference. Finally I took out the hop up and bucking. Reinstalled them with grease on the bucking to seal any air leaks between the bucking / barrel / hop up. That shot the FPS up to 414FPS. But I am still puzzled at why my gun with a M120 spring and stock piston is shooting 429FPS and the other gun with the full upgrades and M140 is only shooting 414FPS. Any ideas? We love the guns and fired them all weekend long. About 3000 rounds through them without a single problem. Perfect, love the guns! (BTW, I'm certain on the chrono numbers. I have my own and compared it to the big red one at the airsoft store, identical readings.)