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.