Keeping a custom shift knob in place

Hello,

The shift knob on my truck is currently part of a gun barrel (I couldn't tell you what gun), and it works, but it tends to slide around/give when I use it. I've been trying to find a way to get it to grip the threads of the gear stick, but so far, I haven't had much luck.

Here's what it looks like:



Any recommendations on how I could get it to stay in place? (You can see it's sort of bent/off balance in the first picture).

 

Some sort of threaded insert to make it actually thread onto the stick would be your best bet. A machine shop should be able to take a piece of flat stock, cut it so it fits into your shifter knob and thread it for you. A cheaper option would be a chunk of wood, same principle, cut it to fit inside the knob and drill a hole so it fits snug over the threads.