Just an example of the real importance of checking EVERYTHING !!!!
A common problem that is often overlooked is shimming badly or too tight
AND a new piston that is a little too tight or binds inside the gearbox....
(Above all else care & attention to detail is of the utmost importance so check EVERYTHING)
Reason being is that many rip everything out and replace loads of new stuff slapping it all together
Then wonder wtf that is a bit slow/sounds crap/getting very warm/hot quickly etc.....
If your piston is binding, your rof is likely to be lower and your amps higher plus gun's efficiency will be crap
Also the piston will be slower to return on release so your expected fps will be down
(Start pushing a gun with a binding piston and PME is likely to occur sooner too)
You don't want to see a very loose sloppy fitting piston with loads of slack moving all over the place
But you need to check it moves freely and falls on its own when fitted inside the box (screws done up)
Here is a pic of a slightly binding piston for somebody with a lower rof than expected issue....
Hence it is sooooooooooo important to pay attention when fitting replacement parts
Fairly sure the picture speaks for itself, but a mild bit of sanding on gearbox rails or piston guides is required
btw the gearbox is standing vertically upright but still the piston does not fall freely
PS - same piston does not seem to bind in a G&G box but never ever just assume anything will work 101%