I have a chamber reamer to chamber the .416/.375 Ruger using the same head space gauge and the same shoulder angle of the .375 Ruger. It maintains all the other standard dimensions as the .375 Ruger.

Essentially it's the .375 Ruger necked up and no other changes!

Is this the same as the new .416 Ruger introduced by Hornady/Ruger?

RollTop

I've just had a 416 Ruger built

The gunsmith used a 375 Ruger headspace gauge, and it works just fine

regards
S&F