Rhop is not a first time mod.. it's a LAST thing to do after you get a solidly working/reliable gearbox with minimal air leak. Otherwise you get shit results with Rhop, regardless of if you install it yourself of if someone who's done hundreds has does it for you. It's not a simple drop in solution.

What you want is a standard hopup bucking, a pdi W hold or at most a flat hop sleeve with a bridge nub, but start with basics.

I recognize all letters, and some words. But have no idea what do you mean. I am a beginner! :) But its ok, see my next post.

Solved!!!!!!!
 

I disassembled mp5 and retrieved hopup unit. After I see it I found the problem: one of 2 metal stabilizers/screws was missing! Without it plastic tan did not pushed rubber into chamber, basically I did not have any spin regardless of hopup adjuster position.
I guess G&G failed with quality control, or sold to me unit was not exactly new.

I put nail into place of missing screw to fix it. Looking forward to test it.

:D