Just curious as they look awful similar, right down to the interlock ring.

Yep!

This is my guess as well.....It wouldn't be the first time Hornady has furnished bullets to the big companies. It's well known that Hornady made the bullets for Weatherby ammo produced by Norma.....

Dumbest thing they ever did was leave the NBT and make that move The old load was bad ass in quite a few of my rifles. The SST just isn't as cooperative.