I took the gun apart last night to see what's in there and do some upgrades.
I was surprised to find that the metal body is the old type that needs to be pried apart, the box and lower receiver did not slide out the back.
The good news was that after taking off the ris and the inner barrel cover I found the body to be compatible with all front ends for mp5s.
The next surprise was that the wiring harness ran all the way from the box to the fuse. No connector at the back of the box, so you have to pull the wiring through. Very simple but unusual.
The gearbox had plastic bushings, not metal as I had been told and had stated earlier. I replaced those with metal oilless bushings.
The spring guide is metal but thinnish and has no hole at the end to make popping the box easier.Replaced with systema bearing spring guide.
The cylinder was smooth on the inside but the cutting around the port was cruder than I liked (slightly burred). Replaced with stock marui mp5 cylinder.
The piston, head, nozzle and tappet plates are all made of that white plastic.
I installed a deepfire piston with all Titanium teeth and a systema piston head with a better o-ring and bearing on the back with a custom hard rubber mount (indestructable).
I tried putting in a set of those new modify modular speed gears but the bushings would not fit properly so I stayed with the CA gears that are stock in jgs.
I did not see the over-greasing problem that used to be common in jgs.
I have yet to get it outside since the mods but I'm hoping for a bit more consistency with the long range groupings. They were not bad but not great before.
Mainly what I put in was to increase durability and consistency. Cuz I'm an ammo dumping whore.
Rate of fire is not very fast due to 1100 mah mini battery in foregrip.
Overall, I'm VERY happy with this gun. Even with $120 worth of new parts, it was still WAAAAYYYYY cheaper than a name brand gun.
Grand Poobah of T.W.A.T.