Ok, so I don't have time to write up a full review, but I thought I should share some required information on this AEG.
First of all, for those that are looking to upgrade this AEG with a rear fed mosfet, you will need to change out the buffer tube and stock assembly, with a regular AEG stock assembly.
The stock assembly that WE is using with the Katana, does not have enough room for the rear fed mosfet to be fed to the stock pipe. It doesn't even have enough room for the Tamiya connector or Dean's connector to be allowed through. This will make maintenance and repair annoying, as you will need to de-solder and solder your connectors on again and again.
WE is on the right: The WE stock pipe does not have the spacer added to the inside of the stock pipe.
You will need the spacer in the AEG stock pipe and you will need to source out a stock pipe screw, that is long enough to hold the WE spacer, that is used to push the Katana's cylinder forward into the hop up unit. You can not have any of the screw protruding from the cylinder spacer, as it will not allow you to close the receivers.
The lower gearbox, is 1:1 TM scale. The internals are also 1:1 TM compatible.
One of the first things that I replaced on the Katana's gearbox was the soft metal 8mm bushings.
I also needed to add a 0.01 shim to the spur gear, as it was rubbing on the bushings.
I can also confirm that vers.II selector plates can also be used, but you be required to remove the spring release arm. I removed this feature as I am using an ASCU that has active breaking and completes a full cycle. Similar to the Systemas PTW.
This is how the gear box came. BONE DRY, with no grease other than the little bit used on the shims. But the gears and internals are of good quality and should last a long time before requiring replacing. The workmanship on the internals seems to be near excellent workmanship, other than requiring the 0.01mm shim on the spur gear, I am quite impressed, when relating it tomany other gearboxes that I have been through.
The trigger switch is similar to the King Arms, low resistance switch and does not use the metal tab on the selector plate.
One last thing is the hop up unit.. It is a copy of the TM spec hop up chamber and inner barrel assembly, but I have found that the replacement of the chamber is a little snug for the Modify Accurate hop up unit. But with some gentle persuasion, the unit fits tight and the airseal I am getting with the Modify unit and WE's cylinder is 99.98%, with no exaggeration.
I am getting 368FPS, consistently, based on 10 shots, using 2 different chrono's.
I have ordered some Sytema PTW spring tensioners, that will increase my FPS, for out door games.
My personal opinion of this gun, is nothing short of amazing.
This is just a quick type up and my person thought s on the WE Katana. I apologize for the grammar, but I just don't have the time, but thought it may help others with any questions they may have.