G&G PM5-A4
I'll start off by saying forget the G5. If you have the option between the G5 and this MP5... you should 100% choose this MP5.
Fitment: Everything fits together quite well, all screws screw into metal and hold everything together properly. The lower is held onto the upper via 2 push pins. This is a fantastic system and makes working on this gun very enjoyable.
Finish: Everything is very good. The black parts feel exactly like they should feel, you get a very strong sense of rigidity.
Barrel + Hop:
Decent hop-up setting, Well cut and crowned brass barrel. Only thing that I didn't like is how the hop-up adjustment arm seemed to be a little big flimsy, but it didn't bother me much once it was inside the gun.
Motor:
This motor felt to have quite a bit more torque and speed than previous versions of the G&G guns I've played around with.
Gearbox:
This is where the problems with the gun are!
Stock this gun was firing anywhere from 341 to 425 at 16 BB/sec... It seems G&G has been paying attention to complaints of poor air seal effecting the FPS... but they haven't done the proper thing by re-designing their shitty piston head... instead they loaded it with a 425 FPS spring hoping this would solve everything.
When I opened it up I noticed that the spring was EXTREMELY poorly coated and already had rust forming on it.
I also noticed the high FPS spring was starting to take a toll on the gun's internals (after under 200 rounds being fired)
Metal Shavings in the gearbox
Chewed up spring guide
Shimming: It wasn't too great, alot of the gears were pretty loose.
All 3 gears had at least 0.5mm of play
I'd rate this shim job a 3/10
Airseal:
As always these parts suck pretty hard. I'd recommend changing them out ASAP.
I threw a Prometheus M90 spring, Systema cylinder head w/ Sorbo pad and a Systema piston head in here...
And this gun is now firing a solid 315 FPS at over 21.56 BB/Second... If you need a BB hose.. with some VERY MINOR changes... this is your gun.
Overall: This gun is WELL worth it. Out of G&G's entire line the G&G PM5A4 and the G&G RK47 (standard model, not the shitty rec version) are the only two guns I would recommend.