I can't say for sure about the .270 bullet but I know both the .308 165 gr hpbt gk and the .284 140 gr hpbt gk are indeed a tougher bullet then the sp gk. I would assume that the same holds true for the .270 offering.
In my experience with the 165 gr bullet out of my 06 it acts like the hammer of thor on white tail. It has always passed through, even with steep angle shots and double shoulder shots, and has always left a silver dollar size exit. I can't say the same for the soft point gamekings as I've had several close range shots that resulted in a bullet failure after a bone strike. This statement is not an assumption as I did recover the deer after a long tracking job. After the bullet hit the shoulder bone it blew apart and only penetrated a couple of inches into the vitals.
In my honest opinion the standard gameking is a great bullet if your shots are greater than 100 yards or you have a lower muzzle velocity. But in my neck of the woods I'm just as likely to shoot 400 yards across a corn field as I am to shoot 25 yards in a tangled thicket. Thats a lot to ask from a bullet but the hpbt gameking has proven to fit the bill better than any. (So far at least)
