pic: we were prototyping and made this sketchy gearbox.

[protoserge]

What kind of shooter wheel are you using? What diameter? Are you using a treaded wheel? I can't see clearly from your photo, but are you using ball bearings rated for the output RPM?

If you separated the tread off a wheel before, what design requirement states you HAVE to spin that fast? Have you tried spinning at a CIM shaft speed or slower? Maybe you will find that you don't need more speed, you actually need less speed.

I don't mean to sound harsh or overly critical, but too many of these shooter designs have not been fully thought out for safe, reliable operation and need to identify the safety and risk of operation.