bigswede, premiums not necessary but are great insurance. I have a 338-06AI and use the Scirocco with great success. I fireformed with Sierra 215gr GK's. They shot great but never ever killed anything with them so can't comment on that end of it. One thing though is that I can't see them being harder than a Scirocco. Look at a cutaway of both and you'll see what I mean. I've shot both elk and moose with the Scirocco's and every time they opened fully and reliably. So gotta believe the 215gr GK would too.
Hope this helped.
