Tried doing some research on it yesterday. Had a guy on another forum post about chucking a file in a vice and taking both ends of the ring and smoothly rubbing it against the mill file. Tried it, and it feels like it almost takes forever to do it to the top rings ?

Anybody have any recommendations on buying a tool for this ? I know there's tools out there but which one would be the priority over all the rest an produces best results ?

 

The one from summit works great. When filing rings your only supposed to take off one side

 

This is the one I have

http://m.summitracing.com/parts/sme-906000

 

Does it matter which side ?

 

I file the side without the numbers next to the edge. Left side

 

Gotcha! Well noted.