[Hellbringer]

Hi,
I did a upgrade to a GR-25 and that did some matenece to my M4 and they are both having the same symptoms and i dont know what is wrong

symptoms are that i have low FPS my m4 has a m100 spring with systema gears. i started to have a problem with the selector plate so i tore it down to replace the selector plate and i found that the gearbox was cracked. so... and i found tha the internals where dirty and taking a tole on the internals so i ordered a new guarder gearbox, guarder cylinder enhancement set (has cylinder, piston, and piston head), metal spring guide, new bearings and a madbull ver2 tight bore barrel. so i built the the GB and i have low FPS the gun before i tore it down was shooting 350-360 and now it is 195-200 any suggestions

now the GR-25 this one is kinda the same think but a little different. bought the GR-25 and it didnt have enought FPS so i bought a guarder sp150 full tune up kit, guarder GB and madbull ver2 tightbore barrel. built the gun up and i get 320-330fps when the sp150 spring should be 490-520.

do you guys have any suggestion on what is wrong?

Thanks
Mike