Hi guys
I finally got the motivation to reopen my gearbox for my KA M4 that had FPS issues since the beginning of times.
Long story short, I have real bad FPS out of my KA, even after having upgraded "almost everything" I could.
Current Setup:
Stock Gearbox shell (King Arms 7mm)
Stock Tappet Plate
Stock Brass Cylinder, unported
Stock King Arms 1 piece metal hopup unit
SHS Brass Nozzle with 1 oRing
Mad Bull Ultimate Bearing Spring Guide - V2
ARS MASK 3G Force DUO for V2 Gearbox (Cylinder Head and Piston Head)
Modify Stainless Steel Shims
StormTech MAX Impact Polycarbonate Piston
Prometheus 300mm 6.03 SS Barrel
Shimmed by gundock, who also changed my gearset for I don't remember the brand but nothing fancy.
Now to the interesting part:
Compression test of piston, cylinder, cylinder head as A1;
When I add the nozzle on the piston head, there's a slight loss between the nozzle and the cyl. head. So I added some teflon tape on the cyl. head. It helped.
Barrel has brand new Guarder Black bucking and nub, teflon taped to barrel
Hopup unit slid on top, teflon taped where it meet the barrel (where the C Clip is)
I put the barrel-hopup assembly on the piston-cylinder-nozzle assembly and tried the compression test again. There's loss, pretty important from the look of it. I added some telfon tape on the outside if the nozzle (I have WAY too much of that stuff
), seemed to have helped a bit, but no miracle here.
From the look, and sound of it, it seems like the hiss is around the hopup arm
As if the hopup unit was leaking air. I'm not sure how/if that is possible at all.
I've been thinking of changing the whole hopup unit for maybe a prommy (Neo Strike) or madbull (Ultimate) one... any recommendations in that regard is more than welcome, but I'm not sure this is really worth it.
1. What do you guys think my problem might be, with these infos
2. Should I change the hopup unit and cross my fingers?
3. ????
4. Profit
Thanks