Re: anybody using Sierra MK bullets for game
In the testing I've done with the 30 cal 240 I've seen no evidence of tumbling. Just a ton of expansion, all the way down to the base of the bullet (testing at the muzzle).
I would expect if any to tumble, the 240 in a 1:10 twist might but it hasn't for me. If it doesn't I don't see why more standard weight for the caliber bullets would.
Something I noticed while sectioning them...it's funny how this "target bullet" has jacket serrations from the hollow point down the jacket nearly 1/2". That's usually a technique used in "hunting bullets" to insure expansion initiates at lower velocities. No wonder these things expand so well at long range. I think Sierra knows more than they're letting on....