But what happened to my Starships are meant to fly. I’ll crank it up now, don’t file a noise complaint as no one with in cooee anyway. 
Ding Ding… Round 2…!!
So, history with these gearboxes, and M100’s…
I tried the M100 in the “longer rattler”… and it regularly seized.
It was struggling with the M100 spring.
Didnt matter… 340 fps out of a M95…!!
So, i started with a M95 on this guy.
Ok… 270-280 fps. Good result, for a shorty.
But, i got to thinking…
What about a M-98.?.?
Custom spring…cut 1 cm or so off a M100.
Longer than a M95…Shorter than a M100…
Spring in the box is a M95.
I cut off the double base spring, and 1 extra coil…about 1 cm.
Cut it off with a Dremel, as flat as possible.
Filed it smooth as possible.
The “cut end” goes onto the nylon spring receiver.
it rotates under compression, without grabbing…
So, hows it go.?.?
Victory, happy dance time…!!
Even when the motor grip screw was threatening to strip…
A bit of motor height adjustment reqd…thankfully this has one…!!
Another reason to get yourself a MPX…!
Happy Days…!!
Jeez now you’re really getting in to it. Bit of customization to achieve what you are after. Well done 
Can I recommend a bearing between that piston spring and the spring retainer? Steel on nylon’s never good no matter how much you deburr it and your spring will have a tendency to rotate under use. 
You can pick them up from any gel blaster shop or ebay, and it’s piece of mind.
Good result on the FPS though.
Nice work mate
I’ve had a couple of nozzle tips come off now despite using a myriad of different glues.
It was dear as poison but I just bought a bottle of Loctite 480 to try. Figure I’m messing with blasters and enough other projects to justify it. So far so good but the real test will be time.