As with most older airsoft enthusiasts, I’m finding myself having more bench-time than field-time these days. Work, family, house.. as the responsibility stack up, the less time I seem to have to hit the field. So the next best thing is bench time; upgrading, repairing, tweaking, testing… I have no shortage of airsoft related projects and doubt I ever will.

For a while now I have been wanting to pick up a complete waste of a gun and see if I could successfully rehab it back to a field-worthy condition. I have done upgrades in the past, even complete mechbox rebuilds, but this time I wanted a real challenge. My requirements were basic:

1) Find a gun I have never owned before.
2) It must contain a mechbox I have never worked on before which at the date of the search, were versions 5 (TM UZI),6 (P90, Thompson SMG),7 (M14).
3) It must cost less than $100.
4) It must be a Tokyo Marui.
5) It must be in relatively poor condition.

A real challenge, but not impossible. Like I said, I have a ton of projects on my bench so I wasn’t actively looking to start this one until I saw a posting on a local airsoft forum for a Tokyo Marui P90. The P90 never really appealed to me. The funky mags, the short inner barrel, limited size battery compartment, lack of accessories and the list just keeps growing. This P90 looked beat.. I mean, border line abused. Being that it fit all 5 points of my project requirements and that I can’t stand to see a Marui in this condition, I decided to pull the trigger and make this P90 my project.

When the P90 got to my door, the first thing I did was shoulder it and just get a feel for it. It’s extremely ergonomic though I can’t say I care for how close my hands are when gripping the forward area. I can deal as I’m sure it will just take time to get use to the feel. After a complete once-over, I found the following problems outside of the gearbox:

– Trigger: The trigger pull is hard, muddy and does not return to neutral once released.

– Red dot: The red dot does not turn on and is extremely loose in the receiver housing.

– Flash hider: Sporting a lovely orange painted metal birdcage M4 flash hider.

– Butt plate: The stock butt plate was replaced with an extender for larger batteries.

– Mechbox bracket: Non-existent! The mechbox was being held in by a plastic shard with a screw.

Left: What was holding the mechbox in.
Right: What SHOULD HAVE BEEN holding the mechbox in.

I have already started triaging and discovered that the missing mechbox bracket was causing the mechbox to slide back in the body when the trigger was pulled, which caused the muddy trigger issue. Once I replaced the mechbox bracket, the trigger tightened up. I still have a ways to go and until the mechbox is in working order I have no definitive way of being positive, but at this early in the project every little victory motivates me to press on.

With a list like the above, I was already starting to fear the conditions of the mechbox and internals. I was right to be worried:

– Mechbox shell: Missing a screw, other screws were loose buy 4-5 revolutions.
– Slide/Lock plate: Missing.
– Cut off lever: Broken & spring missing.
– Wiring: Half-assed wired to large Tamyia.
– Bushings: Plastic and worn.
– Bevel gear: Stripped teeth which sent metal shavings throughout the entire mechbox.
– Lube: The gears are bone dry and crusty, gear grease used in the cylinder/piston.
– Shimming: The gears move in a big way, not a single shim found.

Ugh, what a mess… PERFECT!

I have shopped what I consider the essential parts to get the AEG back to field worthy status and to my surprise it wasn’t nearly as expensive as I thought:

1 x Tokyo Marui P90 Mechbox Bracket
1 x Echo1 P90 / E90 Mech Box Lock/Slide Plate
1 x Echo1 / Matrix Factory Cut Off Lever for P90
1 x G&P Ultra Precision Gun Smith Gearbox Shim Set
1 x Echo1 P90 / E90 Mech Box Screw set
1 x Guarder / Element 6mm Steel Bushing for Ver. 6
1 x Replacement OEM P90 Stock Butt Plate

That totals to about $60 USD before shipping. I already have a stock bevel gear so no need to order another.

To Do:
– Hop-up: I tested the hop up and have visually confirmed that it is engaging. Whether or not it will hold up in the field is another can of worms that I will have to wait for field trials to confirm.

– Inner Barrel: Currently stock, but I do rock Prometheus tight bores in almost all my AEGS.

– Flash hider: I have a few options here. Standard P90 flash hider or go with a longer and run a faux suppressor or the PS90 outer barrel extension. I’m leaning more towards the flash hider and keeping the stock config.

– Mags & Pouches: No doubt I will want a grip of mid-caps as I currently only have 1 stock TM low-cap. To carry the new mags, I have been eye-balling the Bulle P90 mag pouches and am seriously considering giving them a go.