In another life in another century I flew the L-188 Electra, and if my memory serves me properly there were two types of prop available for the Allison at that time. One was Aero Products and had square tips, the other was Hamilton standard with rounded tips. I think the last AP props went out about 1976, so they are probably thin on the ground now. At the time they were preferred over HamStans, can't remember the exact reason, but rumoured runaway prop incidents may have contributed.
