Okay, if you have a 421mg bb traveling at 91.44m/s, it should have 1.76 joules of energy.
Haha, sorry; posted after you did.
4.5mm plastic bbs and co2... a little costly, no?
G&P M4 Sopmod
G&P Mk18 Mod 0
KSC USP Tactical (System 7)
Tactical Airsoft Combat Operatives