air leak ????

[VooDooPeteK]

OK so here's the deal

I had some issues with my G&G M4 so I took it apart and fixed the problems as well as tossed in some upgrades.

Put it all back together and with some time I got it ( to what i thought ) was in good working order again.

Went to a local game and had a few small issues but nothing I could not deal with ( BB feeding while in full auto ).

When I took the gun to the test area half way through the day and shot a bunch of BB off through the chrono it read 260-269.

so I am thinking there might be an air leak somewhere.

What is the best way to test compression?

I don't have a chrono at my place so I wont be able to test what its shooting till later but need to try something lol.

Upgraded parts added where

Madbull TBB 6.03
Modify air seal nozzle
gaurder clear hop up bucking

thanks

[HKGhost]

cover the nozzle with your finger and push the piston through the cylinder. You shouldn't be able to push it all the way in. And about half way in, it should be hard to push with some bounce.

[VooDooPeteK]

then I guess its the piston head or piston O ring. When I cover the nozzle the piston will move with easy to the point I just need to tilt the mechbox back and forth to slid the piston around.

always good when there is a game on Monday and no mail till then to order parts lol

[jtf2-phalanx]

Did you have this problem before you upgraded because it's odd that you get this issue when you've only changed the nozzle. Try testing it without the nozzle while covering the cylinder head nozzle.

[VooDooPeteK]

I never put BB's through the chrono before this as the gun was stock and shooting ok

I added a spring as well forgot to mention (M110), this is what got me thinking something was strange

[Con Murder]

G&G piston heads are not the greatest for compression (CAS for certain, might not apply to the reg line). In total I tested three seperate piston heads and ended up changing the o-ring from a stock JG to put on a modify piston head for my friends mp5 a5 by G&G (CAS) and I know at least one other that had the exact same problem. That said you can test this by putting your whole compression set (cylinder head, cylinder and piston+head) under water. By plugging the nozzle and placing the piston just in front of the port before submerging it you can see bubbles if it leaks. You can also test the barrel and hop rubber by chambering a bb with the nozzle forward, remove mag and battery, shine flashlight into mag well and look down the barrel to check for light. No light no leak.

[VooDooPeteK]

yea piston head for sure I will order, sucks cause today was the first chance I had to look at it and there is a game on Monday lol