Very low fps on M4

Leftyflip

Well,
I finally got my new piston head and fitted it into my gearbox,
so I put it alll back together and pulled the trigger,
it fired the bb with less speed than a cheap holiday springer :(:(
What have I done wrong? Some wonderful person help me, I'll give you a big hug too.

EDIT:: Wooo now my semi-auto works xD

Hunter1100

Check the O rings on the piston head and cylinder head, and mabye the hop up. Same thing happened to me turned out it was the piston head O ring

thermo

1;did you do anything with the hop up?
2; did you lube the piston?
3; was the piston o ring seated properly? (also was it new?)
4; did you try cleaning the barel?

Leftyflip

thermo wrote: »

1;did you do anything with the hop up?
2; did you lube the piston?
3; was the piston o ring seated properly? (also was it new?)
4; did you try cleaning the barel?

1) Hop-up is fully off
2) Yup, used some silicone grease
3)Not sure will check now, and yes it is a Systema Duracon piston head
4) My barrels alwayss clean :cool:

Masada

did ya test the compression? do this by pushing the piston into the cyliinder and capping off the cylinder head with your finger. the piston should have a lot of resistance there. if it goes in no probs then you either need to lube the o ring or get a new one. oh, and just use silicone oil on the o-ring, not the actual grease.

Leftyflip

All fixed as off a couple of hours ago, thanks lads!
Now you tell me to use oil!!! AARGH!!
Does it make that much of a difference?
THe thoughts of taking it apart again!!
OH well best take it like a man...

Single Malt

Grease is fine...as long as you only use a minimal amount. The thinnest film of grease on the O-ring and a little on the inside of the cylinder. Grease, while slowing the piston action initially, does prolong service life. This means you can get longer intervals in between services of the GB. Oil will not have the same staying power as grease, leading to more frequent need of service.

Masada

no, defo dont use grease, because of its thicker density it has a tendency to make the o-ring stick to the inner edge of the piston head as aposed to moving around freely. i like to remove the o-ring, spray the cylinder head, reinstall the o-ring add some more oil aswell as a nice layer inside the cylinder. you'll notice far better consistency between chrono readings after this.

while its open you can wrap the cylinder head with some PTFE tape to give a rock sollid seal too.,

peter-pantslez

Masada wrote: »

while its open you can wrap the cylinder head with some PTFE tape to give a rock sollid seal too.,

do you wrap the ptfe around the o ring?

or where do you wrap it?

Leftyflip

I guess I owe Masada a big hug soo...

Masada

peter-pantslez wrote: »

do you wrap the ptfe around the o ring?

or where do you wrap it?

yep, pop out the cylinder head from the cylinder and wrap a layer of PTFE around it, then stick it back in. it'll be a lot tighter and a lot better at holdding a seal.

peter-pantslez

cheers richie il try that i put a new ms90 spring in an aeg and its still only firing at about .59