Very nice Mrgreen. Having several pistol myself, I like it.
I thread my .44 rims with a 4-40 thread. If using a PB switch, I use the C&K switch which has the 4-40 thread. If using a touch, I use a 4-40 nipple and insert a 12 gauge solid copper wire for the contact point and a 4-40 nut on the inside.