Magnum cam woodruff key

I believe the cam, sprocket, and bolt/washer will keep the key firmly in place, even if sheared. The cam bod keeps it in from the rear, the sprocket retains it radially, the bolt keeps it from coming out the front. IIRC.

The key carries little if any load and is designed to shear, but if the fit is sloppy, your cam events may be advanced or retarded.