For my 102/105 BMEs I always folded a piece of 320 grit wet or dry sandpaper in half, giving me a piece maybe 2" by 2", rough side out. I cut out a center hole to clear the prop bolt and placed the paper between the spinner backplate and the prop. After tightening it down properly, I had zero problem with slippage. The spinner backplate had a pair of holes to match the allen bolt heads on the engine thrust face effectively pinning them together, and the sandpaper increases the friction available so as to more effectively prevent the prop from slipping on the spinner backplate.

This also worked fine for wood props on my 110X, but when I used a Mejlik 28x10, I got slippage. From a piece of 1/8" music wire, I cut a pair of pins approx 1 3/8" long. I then drilled an 1/8" hole in the spinner backplate about 1" from the center of the 7/16th" prop hub hole, and another 1/8" hole also about 1" from the center of the prop hub hole, but 180 degrees on the opposite side of the prop hub hole (so all three holes are in line). The measurements don't have to be exact and exactly on a line, because I use the backplate as a drill jig to exactly match the 1/8th" holes in the spinner backplate with holes in the prop itself. Just place the prop and spinner backplate together (facing properly) and insert a 7/16th" drill bit to center them up. Then dril the first 1/8th" hole all the way through the prop and insert one of the music wire pins to hold alignment. I then drill the second 1/8th hole and they automatically match exactly. Same for any new prop I want to use.

After the holes are drilled, I epoxy the pins in the prop. The reason they are approx 1 3/8th" long is so they will extend all the way through the prop, and also all the way through the spinner backplate holes. I still use the sandpaper for added friction, and even the Mejlik has zero movement with proper tightening, sandpaper, and pins.