[MikeG]

David, that sounds pretty hot! The .300 Win Mag (essentially the same case capacity if not a bit more) shows 125-130gr. bullets in the neighborhood of 3400fps, 3500fps tops. Although the 125gr 8mm bullets should be slightly shorter, resulting in more powder space/less friction, that's still quite a gain.

I'd suggest running the numbers through Quickload or something similar, just for a sanity check.

 

[MikeG]

Well, looking at the load data, you are definitely 'full throttle' but uniformly a bit above .300 Win Mag data (for the same weights). Although your 250gr. loads look to be a bit lower than what the .300 Win will do with the same bullet weight.

It does help that you are using standard-type bullets, nothing fancy or extra tough, like the X or Failsafe.

Of course I don't have any idea of how smooth the barrel is or how deep the throat is cut.

With the longer barrel... I would say that makes me feel a little better about the velocities you have published, but I'd wager the pressures are at least at SAAMI max for the usual belted magnums.

Still, it's true that every rifle is an individual, so good luck, and stay safe.