I took my Searcy .500 NE out to try out some of the fiber optic beads available from NECG. The target below was shot at 60 yards and shows the results.

The group in the X ring was 2 shots of 570 grain Woodleigh solids, using a 6 o'clock hold. Since that was too high, I switched to the next lowest fiber optic bead.

Then I shot 2 more shots of the Woodleighs, but apparently was not concentrating well as they spread a bit. Then 2 shots of GS Custom 570 grain FN solids grouped well for a dead on hold. Finally 2 shots of Bridger 550 grain FN solids grouped well. It looks like this bead will work fine for a dead on hold.