I don't doubt anything you stated. Whats strange is that I read some guys had them to pencil through game without expansion and others reported over expansion & blowup as you saw. I wonder if some of those guys were actually shooting the tipped match king and got mixed up thinking they were a tipped game king.I don't think they have thicker jackets at all. I think they're the worst bullet I've ever shot thru my 264 win mag. Running them through my milk jug test at 100 yards, they only penetrated to the 3rd jug, and all that was left was dust and tiny pieces of copper jacket. My 257 Robert's with 100 grain bullets even makes it to the 4th jug and retains about 70% of weight. I bought a box of 100 to try. Loaded up 3 rounds with same load as I load swift sciroccos. Shot 2 to see if they were about the same poi as the swift's, which they were, and shot the 3rd round into the jugs. The other 97, I gave away. I'm done with sierra anything. For hunting, I'll take swifts any day over anything. Killed a 300 lb boar hog last fall with my ruger no 1 in 25-06, and 100 gr swift a-frame. Dont get any better than that.