One Shot Airsoft Gearbox Shimming Tool
(Type: V2 Gearbox)

"If anyone is looking for instructions, found some here

https://1shotairsoft.net/

"I got one of these from the guy who originally invented then down at the antioch outpost. You'll need a set of calipers to use this correctly.

Line up the holes, loosen the screws on the 1shot until the snugly press against the gearbox, separate the gearbox shell and measure the total height of the screw and 1shot for each post.

Then measure the height of your gears not including the part that goes into the bushing / bearing.

Subtract the gear height from the 1shot height and thats how much shimming needs to be done.

Saves a lot of trial and error if youre trying to get that perfect shim height

"I have mixed opinions on this tool.
To begin, the tool came in a small plastic bag with no instructions. Instead of the silver pictured, mine came as a dark blue, which I think looks cooler. Before I began using it, I noticed that the screws were super easy to turn, even from a light touch of my finger. To alleviate this, I unscrewed all three screws and applied a generous amount of thick grease to each one. My thinking was that it would add a slight bit of resistance to each screw, making the measurements less likely to be accidentally messed up. After inserting the screws, I wiped the grease off. I think that this problem could’ve been easily avoided had the manufacturers decided to put a small spring in each hole, adding tension to the threads on each screw. I might do this in the future myself.

How it works, I won’t explain it here, but in the comments, you can find the website with instructions. I was shimming because I was installing new bearings into my gearbox, and I found that I could use this tool as a clamp to hold them in place while gluing. This worked surprisingly well.

Important note: in my experience, the measurements taken from this tool were only a ballpark, I still had to do some work to get the proper shimming. Mind you that I am an amateur tech, I have shimmed my gun ~3 times now, over the course of the 2.5 years I have been playing airsoft.