I have been searching for some good information on this cartridge but have only been able to find out basic information about the case. Does anyone know some specifics on this cartridge? I am looking for things like case length, shoulder angle, etc.. I am also wanting to know if most people are using the 300 Winchester case or the 300 H&H as well as details about their forming methods. Also, if anyone has any performance data with 168 gr bullets I would appreciate that as well.
Thanks,
agr516

This was the favorite cartridge of Warren Page. Page was the gun editor for Field and Stream about the same time Jack O'Connor was at Outdoor Life. Page was a benchrest expert so I'm sure somewhere in one of his old articles or books is a discussion of that cartridge.

Forgot to ask why this cartridge? It was built on a 300 H&H case and to me winds up being pretty similar to the 7 STW which is commercially available.

Mark Dobrenski who posts on here uses one, if you PM him he could probably give you all that info. As far as I recall, it was a 7mm on a full length 300 H&H case. There were two Mashburn 7mm's though, one on a shortened case. As mentioned, basically a 7 STW by another same, some slight differences in case design. - dan

I am looking for the 7mm Mashburn that uses a case that I believe is shortened to 2.630". The reason that I am not going with the STW or ultra mag is because although they would fit in my action, my seating depth would be controlled by my magazine length. I am ultimately looking to shoot 168gr Berger VLD's to a velocity as close to 3200fps as I can get.

Based on my STW experience I have trouble seeing a STW moving a 168 at 3200 unless it has a REAL long barrel. Curious how a smaller case would do it.

I sent you a pm the other day (I think..), 7828 with a 25"-26" barrel should get you really close. R25 would be the second powder I'd try.

Mark D

Hi Mark. Glad to hear you're still alive and kicking. On the STW speed front, I find RL25 gives me better velocities with the heavier bullets. That's in a 24" barrel though. - dan