Re: SMK 30 Cal. 175 problems
It's possible Sierra changed their pointing die since the last lot for those bullets you have. And the one that formed the front half of the bullet may well have been a bit different than the earlier one. Unless you've shot the new batch of 175's, they're just different, not bad. Correctly seated for accuracy, they may be better than the old ones.
Send Sierra the lot number of your old batch (if you've still got the box to read if off of) as well as the new batch asking if they changed pointing dies on their production line between them.