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300 Mashburn Super

8K views 6 replies 5 participants last post by  jan byler 
#1 ·
I might have an opportunity to pick up a Mod.70 pre-64 in 300 Mashburn Super, but aside from hearing the name I know very little about it.
Would someone know what cartridge its made from and what it might compare to performance-wise ?
It seems like the necessary dies would be no problem as they are advertised, but is it worth the trouble to play with ?
Any info will be greatly appreciated...
 
#3 ·
I would look first to the condition of that Pre64 M70! If its in nice shape and the price is right it might be worth the fun of ownership.

I would not trust any part of that chamber markings. Have a chamber cast done and slug the bore.

The 300 Mashburn Super and Short magnums are listed in Ackleys book. Even then........... be safe.

Don't fire other cartridges in it such as the 300 Weatherby. That round requires freebore to be safe. Even then ............

As I said for the right price it might be fun to play with. If it has the original 300 H&H barrel then even more for its looks. They are heavy however but that would be a cannon loaded safe.
 
#4 ·
according to Ackley's handbook volume 1 the mashburn super mag. is slightly larger in case capacity than the 300 weatherby. it also states that 300 weatherby factory ammo can be fired in the rifle and that mashburn does not recommend freeboring rifles in the mashburn cartridge due to accuracy loss. so yeah, you could use weatherby brass and fireform for the msm cartridge.

COOL!!
 
#5 ·
big dan,

I knew thats what Ackleys book says however I remain cautious to recommend that a chamber cast and bore slug be done. Ackley was on the edge in my view to suggest firing ammo loaded for a freebore in a non freebore chamber.

Pre 64's are great guns. It could be fun done safe.
 
#6 ·
Thanks for the info fellas, as much as I love playing with wildcats this one had me stumped.
Having read some of Warren Page's writings decades ago I was a bit familiar with the 7mm Mashburn but not a 300.
From what has been said I'm guessing the parent case is 300 H&H which is ok as I have lots of that.
At this time I am trying to find out more about the rifle before making the plunge.
Thanks again, and much appreciated !!
 
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