I had the chance to get my hands on a G&P i5 gearbox recently, thanks to Gunny87. So while I have the chance, and as it is pretty new, I figured I would do a write up on its features and my thoughts and opinions on it.
So let us start with the outside of the gearbox; Right side
Use G&Ps standard 2mm hex screws:
3 short above the cylinder
5 long along the bottom
and a single short screw about where the trigger axle would be.
Along the top toward the front of the gearbox, both above and below the cylinder, there is what looks like the facilities for a mock bolt and bolt catch very much akin to that on a Krytac. But unlike a Krytac, there is a rectangular hole just below the front of the cylinder that provides access to the tappet plate spring, similar to the design of the V7 gearbox. A nice feature to further release spring tensions before opening up the shell.
Moving further back, there is a large plastic rectangular box. This is merely the top protective housing for the electronic trigger board.
Behind that, there looks to be a slightly modified ambi bar hole, for what I imagine to be future options to add an ambidextrous selector switch or for models that might include that feature.
G&P's standard 8mm bearings. Some of the best stock bearings in my opinion.
A small hole for easy access to apply lubrication to the gears.
And in the rear, added support around the rear body pin hole. I could see this potentially causing issues with receiver fitment and/or alignment, but could also aid in those as well as stability.
Flipping over to the left side of the shell:
Again in the front, with the Krytac-esk bolt catch/release system.
Groves with little tabs to retain wires for front wiring configurations.
Proprietary selector plate that appears to be a hybrid of sorts. It is similar in function to that of Ares with a small magnet imbedded in the plate and with a tab that moves above the trigger for the safety. The other half of the plate looks to be about the same as most V2. It has a spring secured by a 2mm hex screw that gives the selector tension and stability.
Under the selector is the electronic trigger board. Secured by 3 small Philips head screws. When the screws are removed, the board just lifts right out.
Moving around the lower and back outer edge of the gearbox is a convenient channel for the wiring. This helps to separate the electrical from moving mechanical components and potential damage. But the damage with this design can happen more so during assembly/disassembly if proper caution isn't taken as the wiring passes under where the grip alignment ridges go.
Then all the way in the back is the mosfet held in by 2 small Philips head scews
And on top, probably the most notable feature of the system, the quick change spring guide through the top of the gearbox. Requiring only to take off the upper receiver and buffer tube screw and to pried out with a flat head or similar tool. But this also requires the piston to come to rest in forward position, which can be difficult as it is recommended to just cycle the gun and hope it ends up fully forward.
The electronic trigger board
Mosfet
Inside the gearbox:
Standard G&P compression set, including a tapered cylinder, metal cylinder head, metal O-ring nozzle, and G&P's 3 port "jelly bean" piston head.
Could be just with this specific gearbox, but this one has a 14 total tooth piston, with the 2nd to last removed and the last 3 release teeth being metal.
To pair with the 14 tooth piston, a 14 tooth sector gear. From counting teeth and using an online calculator, it has a torquier gearset in the 25:1 ratio range.
The sector gear looks to be pretty on par with previous offerings from G&P, but the spur and bevel are a little bit different. The bevel has what seems like a nylon buffer set into the top of the gear. My guess to reduce friction and possibly to adapt to tighter shimming. The spur looks to be made of a better steel than what I have seen in previous G&Ps.
The tappet plate is proprietary, but does not look too far off to where a standard aftermarket part can't be modified to work. Proper measurements and cuts for material to be removed and I could see any standard aftermarket option working.
In the top half, only 2 things of note really:
-Proprietary trigger/trigger spring
-And the top casing for the electronic trigger board can be pushed out.
It doesn't have the old style of shell reinforcement so low ratio gears are an option.
COMPATIBILITY:
Compatible with standard TM spec parts:
-Piston
-Piston head
-Nozzle
-Cylinder head
-Spring
-Gearset
-Bushing/Bearings
-Anti Reversal Latch & spring
Potentially compatible with modifications:
-Tappet plate
-Spring guide(would still take standard spring guides, but the quick change feature wouldn't hold)
Proprietary:
-Gearbox shell
-Trigger
-Wiring harness/Mosfet
-Tappet plate spring
FINAL THOUGHTS
Overall, it is really nice to see innovation and new products and parts coming from G&P. But I wish there was just a couple more things, even just one, that would have been incorporated into the shell; an anti reversal latch release. This would make releasing the spring tension and swapping springs MUCH easier, as well as just better for the gun all around. There are numerous ways it has been done by other companies before such as ICS and G&G, or they could have even just drilled a hole in the shell similar to that on VFC gearbox shells.
This is NOT the gearbox for anyone looking to drop a Gate Titan, BTC Chimera/Spectre or other TM spec V2 style trigger board mosfet into.
