My Brownells .245" 60 degree dovetail cutter, the smallest offered, finally arrived, so I hacksawed off a thick, coin-shaped slice from a 416 stainless .750" bar I had lying around, trued it up, milled it into a semi-circular shape, and cut the male dovetail to .250", .005" wider than the female cut will be. I like using the same cutter for both, and I also like cutting the whole dovetail with a dovetail cutter. Many gunsmiths pre-cut a slot with a standard end mill, then cut the dovetail, but I have found the dovetail cutters cut better with full contact on the cutting edges, even if it induces more wear and tear on the expensive cutter. You need to take it very slowly, but it works just fine. Then, I cut the .245" into the barrel:
I cut the coin extra thick to allow heavy beveling of the dovetail leading edge but still be able to clean the bevel off when machining. It still didn't "bite", so I widened the female dovetail a bit, and the blade started to bite. I drove it about a third the way in using a brass punch and steel hammer, confirming the proper tension, then drove it back out and ground the blade closer to final shape. With the blade all the way in and protruding sufficiently on both sides, I machined the sides down, hoping to make the dovetail nearly invisible:
Off course, one wants to leave sufficient height for regulating the sight blade...you can always remove extra material, but it's much harder to put it back on...so it's about .070" tall, giving it a slightly cartoon-ish look, but removing that .070" or so will make a huge difference in the appearance. Also, while I'd like to say I planned it this way, the blade width just happened to turn out just right; it's a bit narrower than the original, but because it's closer to the rear sight, it's nigh on perfect, showing just a sliver of light on both sides:
I still haven't found a center drill long enough and small enough in diameter to drill the ER detent hole, so I'm dead in the water right now. When I do find one, I'll remove the barrel for the last time, install the detent, grind the blade down to final shape, polish her up, and be done!
TBR