I had a pack (think I still have some of them stuck back somewhere) back when they first hit the market--don't remember if they were screw-in or glue-on (think they were glue-on). I didn't like them because the blade was secured to the ferrule with a roll-pin, which worked loose. If I ever used them, it wasn't on anything larger than a rabbit. Very sharp out of the package, but that's as far as I got with them. I figure the design has changed since--that was several years ago.
Chad
Chad