It is fun to shoot a buffalo at 10 yards. But sometimes necessary also at 100 yards! So good to check it out at that range as well, as to how it shoots.

Is that load crossing by 50 yards? ie the "superimposed"?

"back to the scope question: there are two 1" long narrow grooves machined down each side of the quarter rib, and a single shallow 1/16th" long blind hole on the top of the quarter rib. I am presuming this is some sort of facility for a Heym proprietary scope mount? It would seem to me that maybe this may be something the factory uses simply to test regulation?"

A photo would help, but are you describing claw mount grooves or something shallower? Generally I would have thought four grooves in that case?

In any case I would NOT bother with a scope on a .500 NE.