The Berger 338 Hybrids came from 3rd Gen the other day an all I've done is oogle at them.
They look to have spent a bunch of time in the polisher. Don't don't know if that's good or bad. Though I don't like to see jackets any thinner than they need to be.
Cosmetically they win the beauty contest with the SMK. However, from the many SMKs that have penetrated my 8" very fine sand backstop the Bergers will have perform pretty well to keep up. If the sand contains any moisture at all, the second shot out of the RUM always completes penetration. I have to wack the backstop with a sledge hammer between shots to keep bullets contained. (I've since piled lava rocks behind the backstop to contain things)
The Hybrids are definitely long. About 0.090" longer than the SMK with a bearing surface that is about 0.009 shorter. Diameter of the Hybrid is slightly less than that of the SMK.
When seating both bullets on the lands (for the first setting for the Hybrids) the cartridge base to ogive measurement is an average of 3.052 for the SMK and 3.125 for the Hybrid. I'm a little confused by the difference in these numbers as I let the chamber seat both bullets in a dummy case.
The attached pic shows the Bergers produce a longer overall cartridge length. The appearance is exaggerated a bit by the angle of the camera and placement of the SMKs in the next row back of the loading block. The overall length of the Hybrids is 3.9 inches (just barely long enough to prevent fully extracting a loaded round with out releasing the bolt. The SMKs overall length is is 3.8" a full 0.10" shorter.
As the bearing surface and diameter of the Hybrid is a bit smaller than that of the SMK I figure I'm safe in using the powder charge that has been developed for the SMK.
I'll shoot these six shots tomorrow in a round robin fashion and see what happens.