New piston - still low FPS?

[Priestpel]

Had a game a week ago and by the end of the night (very last game, lucky me) the gun was making horrible noises after afew shots

Got the rifle checked out, turns out the piston had just started to strip so I got a new one. Tested the weapon today because my game go cancelled tonight and I was going to get it chrono'd to see if the FPS has improved. However, just by testing it out it seems the same...

This is an ICS M4A1, standard gearbox and motor with a Prometheus M110 spring (the spring should definitely give me a high FPS as far as I can tell) but it was last chrono'd at around 280-290fps before the piston was replaced.

Thoughts on the subject and possible things to look at would be appreciated.

[humphriesryan]

Re: New piston - still low FPS?

It's ur airseal u need to sort out bud

[a_flea]

Re: New piston - still low FPS?

+1
Have you tried a compression test (your thumb over the nozzle)?

[centaur]

Re: New piston - still low FPS?

Some prome springs are lemon........installed same spring several years back and fires almost identical as yours, same set up with guarder SP90 was able to squeeze a max of 381FPS, there were no double O ringed cylinder heads before, but was able to seal it up properly.

[Priestpel]

Re: New piston - still low FPS?

na, my technical knowledge is zippo really. i shall google the compression test and see if I can get my hands dirty when i get a chance.
I do have the original spring i believe, but dont exactly have a chrono available =P

[Priestpel]

Re: New piston - still low FPS?

passed the compression test by the looks of it....
only thing i've noticed is theres no screw at the back of the gearbox? if tht make any difference at all

[Priestpel]

Re: New piston - still low FPS?

Found wot looks to be a new piston head, which was slightly different to screw on but im hoping wont explode....
Spring seems to be under more tension now when I placed it back inside the gear box, so I'm hoping the issue will be resolved...and not explode

[sparrowhawk]

Re: New piston - still low FPS?

if your piston head is beefier,making your spring more compressed,then you should check your angle of engagement AOE,the angle and position of where the sector gear first makes contact of the pickup tooth on the piston rack, if your sector gear is picking up your piston rack in a different position it could rip your piston teeth off, unless the material on your piston is stronger than your sector gear it will rip the teeth off your sector gear instead