Widening a reflector to fit an xhp50 - need advise

I have fw1a reflector I want to widen to xhp50.2 spacer. Considering the reflectors finish is susceptible to damage. Any tips/tricks to prevent damage to the finish as I bore out the hole?

Use a reamer, #26 straight scalpel blade to tidy up from the outside back end, make sure any swarf stays out of the reflector. Go slow, check progress in small increments. I wouldn’t use a drill bit.

Thank you, any specific reamer in mind to enlarge 7mm to 9mm diameter?

Djozz likes this type.

Or there’s this type.

The hand held linear smooth edged ones would be best probably but there is the stepped variety too which may make less of a conical hole if you find the right size.

Good stuff! I’ll try a hand reamer, thanks for the protip!

Harbor freight has some stepless drill bits that work well as reamers. Their hexagonal ends fit into a typical screwdriver.