Nah he just got it used. OP make sure that the magazine is filled up. Unlike TM magazines, KJW ones don't spray gas out and you should be able to hear when's it's filled. When you get 3 or 5 shots, do gas vent out or is it actually out of gas? Do you have a video of the problem?
Originally Posted by mansopoor
If I push the button at the top of the mag for a few seconds at the same time as I start to fill the mag and the let it go and continue to fill the mag i get 10-25 shots off
Perhaps the magazine valve is faulty? Make sure that it's not leaking.