What "radius" for XM-L reflector?

I am modifying a mini-mag incandescent reflector for a custom XM-L project I am doing. I am going to sand down the reflector a bit, but how much? Assuming it was an aspheric reflector, what would be the best radius for an XM-L (u2)?

Thank you.

Here is the viewing angle of the XM-L

weegidy said:

Assuming it was an aspheric reflector

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You mean parabolic reflector. Are you looking for the radius of the opening you will need at the bottom of the reflector? (the vertex opening) The dome of the XML is a radius of 2.26mm, so you want the vertex opening of the reflector to be at least 4.5mm in diameter which is about .180".

There are aluminum reflectors for sale at the sandwich shoppe which will fit the mini-mag. The McR-16 and McR-18 specifically. You might ask the shoppe if either need modification to fit. Both of those McR reflectors have a vertex opening larger than .180".

Perhaps there will be some relevant information in the mini-mag modders guide.
Also: tips for cutting down stock mini-mag reflector.

The minimag incandescent reflector is focused inside its parabola. It's aimed for a filament about 2mm above the 'base' of the reflector. Put the LED here or you'll get much-worse-than-usual rings.

Otherwise, you're seeking an optic or reflector that physically fits.

AnAppleSnail said:

It's aimed for a filament about 2mm above the 'base' of the reflector.

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Perfect. I'll give it a try. Thanks a lot.