KJW G27 low fps and puff of gas from behind
 

I have a KJW G27 upgraded with Guarder Recoil spring and rod, knocker spring.
I have low fps compared with my other pistols and the first shots always a puff of gas come out from the back.

I tried to swap the mag valve with one of a WE mag but nothing change. This valve works well in my WE G19 but in my G27 not.
It seems that my G27 has low knocker strenght but I inspected more times the trigger knocker parts and everything seems ok.
What can I do?

Sounds like you have a cracked/broken nozzle.

Nozzle already checked, it's ok

It can still be cracked even if it doesn't look like it.

Nozzle inspected and it is good but swapped with another stock one. the pistol works a little better but it lacks of power.
For me it has a weak valve knocker (already upgraded with guarder spring) or KJW Mag valves are not working properly,
I tried it with my WE G19 magazines but they works randomly in G26, but when they works the shot is more powerful

Well the Glock series is the worst of the KJW guns. I've always told people to stay away from them.

I am planning to rebuild it with upgrades. Guarder now sells steel hammer hausing kit that may solve the issue

With the puff in the back in mind how often to you oil your pistol?

I clean and oil with silicone very often, after 100 bb's fired

Ah ok i figured id ask because i had a simalar problem happen with my w.e glock 18 and as an attempt to fix it i put a small amount of oil in the top of the slide about 4 drops at most on the inside of the nozzle letting it sink inwards and a bit more on the outside of the same peice only on the back and after sitting for 2 minutes i functioned and as i dry fired the gun the back spray went from almost a quarter of the gas to normal and alot of the power came back as well