AK 47 Iron Beast Charge Shot

Hello, the charge shot is for me useless, most of the time he isnt working if i try to kill a enemy in front of me, why the chargeshot is not like the chargeshot from the M240B tesla and only for ZM games? What think the GM of this and what you guys think, for me the Chargeshot from the ak 47 Iron Beast is very bad and not perfect at all!