OK, I drilled and countersunk the sprue plate. I used an aircraft rivet microstop countersink,
and it cut the 4130 like butter, good surface finish, easy-peasy in drill press. Drilled 3/32" pilot
hole and the countersink has a 3/32" pilot snout, so it followed perfectly. Pushed it thru until
it was sharp. A bit of lapping of the plate on both sides on 240 grit on my table saw cast iron
table cleaned up scratches and burrs.
I am sorry to see that the threads down in the mold, where the lock screw threaded hole
intersects the sprue plate hold down screw hole are somewhat boogered up, and it messed
up the bottom portion of my nice new thread.....first time in, before I had hardened it.
But that is just appearance, it works perfectly.
Now I need to find a #10 wavy washer or similar, and will then clean the cavity with a bronze
brush and see how the old girl can make bullets.
And with the plate opened.
I am pleased. The plate may need a bit more trimming around the edges, that one edge is pretty close to the
cavity (but does clear) when the plate is open.
The countersink looks a lot like the factory one, and is 100 degrees.
Bill