That co2 mod kit for mid price range svd dragunov,s

[Ivan1980]

Hi guys and girls. 

I have been wondering for ages 

How the hell does this thing work.

I own a svd with that Co2 gimic that replaces a manual spring action. 

I admit I may be a bit simple but for the life of me I can not see how pulling the trigger actuates that system. 

Its a mystery to me. 

You skrew in a co2 bulb put it in the gun with that light positioning spring. 

And for some reason after manually cycling ,it fires . 

God I would love to know what is happening to make this occur. 

There must be unseen connection,s associated with pulling the trigger. 

All I can see isca redundant sear from when latched onto a big spring piston pre modification. 

Amy clever people wanna tell me ?