Kieth, the brass blade is 0.286" overall top to bottom and 0.302 long (measured while removed). I think it original to the barrel, both have remnants of old black paint on them.
The bottom of the slot for it is 0.468" from bore center and the top is 0.596" - so the barrel blank had to start out at least 1.193" diameter to have enough material for it (if that's how it was made so no metal had to be added), the barrel is finished to 1.027". I always 'thought' that these were made bu turning the barrel to size front and back of the sight leaving a ring that was then contoured in a shaper, slotter or similar machine.
I have another one that I know is a replacement in a 22 HP barrel with the silver brazed base that is a lot taller at about 0.350" - I think that is a lot taller than needed for that gun, it has enough grooves that it could be shortened. It's just a little longer at 0.313". I also have some inserts hiding somewhere.
