The Mashburn has no performance advantage over the 7 Weatherby, or 7 Dakota for that matter. The case sizes for all three are just a touch bigger than the 7 Rem Mag. I consider 7 Weatherby data as a max velocity for the Mashburn. Amazingly 7 Rem Mag max charge loads in my Mashburns usually outperform 7 Weatherby book velocities.

The advantage of the 7 Mashburn over the 7 Weatherby is brass availability. There are several sources of high quality 300 Win Mag brass and less availability, at higher cost, of 7 Weatherby brass.

But if you are willing to get the 7 Weatherby brass it’s a darn good round. Same as the 7 STW (brass availability), 28 Nosler (one source of brass, availability), 7 RUM (availability), 7 Dakota (one source). They are all good rounds.

Then there’s the wildcat thing. Advantage or disadvantage depending on the person.