KJW KP-05 inconsistent shot count
 

I do have this in For Sale forum but may withdraw it. As I said in that thread
I am getting fewer shots per cartridge. In past 2 days , however, I got 36 shots from 1 cartridge , 20 from another and 57 and 52 from two others.
I can live with these inconsistencies if I knew what is causing it.
Can anyone explain what the problem could be and a do-it-yourself repair?
As an unskilled novice is seems that internal gas management is the issue.
Thanks!

My guess would be you should look at the valves and o-rings and clean and lube the internals of the gun.