G&G RK47 blowback issues

[maffiozo1234]

Hi all, 

Ive got an early g&g rk47 (i believe its about 15-20 years old) Im a decently experienced tech but its developed a new issue that I just cant seem to fix.

In semi auto its shooting at 100fps roughly, but in full auto its shooting at about 300 ish (both on 0.28s) 

Apart from this the RIF has no issues, the EBB works, and the hop works (when in full auto) 

Ive checked compression and its good (as can be with the EBB system)

Any advise welcomed. TIA

 

[Leo Greer]

Sounds like a tappet timing issue. Where does the nozzle end at after a shot in semi? Is the tappet plate intact and undamaged? Nozzle centered?