KSC G18C problem

[burnettkyle]

Hello i am haveing problems with my G18C. I have used the search function and found nuthing. sorry if this is a repeat question.
The slide on my G18C gets stuck about 2 cm from the fraim on the return after the third or fourth shot then all the gas shoots out is there a fix for this lubing or metal slide any thing to fix this problem. also the gun has beed double feeding bbs into the barrel. How can i fix these problems any help appreciated.