Stingers are built with a modified tip - no, all COI resharpenable type broadheads I field tested myself tip curled from somewhat to terrible bent.
Zwickeys were the best. All others were bad to terrible.
Field tested on animals? That's what Dr. Ashby has done for us. He got tip curling problem pretty muchworked out by modifying the tip(on game anyway). Grizzly's always ended up best in his tests. But like Chad mentioned, I also have a problem sharpening a snigle sided blade.
Man, you must have really had some serious power behind thoseheads to bend them so bad.
Also, send the Magnus back, they'll replace them free.
Personally, I never had a problem with tips curling unless I hit a rock or something. But never on the North American game that I have hunted. Never hunted anything like African Buffalo though.On my upcoming Moose trip, I'm planning on using Stos two bladed with my Howard Hill Longbow (74#'s at 29").