Just out of curiosity, what is the practical difference between a 7mm Mashburn and, lets say, a 7mm Weatherby? The most recent Nosler manual shows about 3070-3090 or therabouts with a 175 Partition in the 7mm Weatherby with a 24 inch barrel. I do not have any loading data for the Mashburn, but most people seem to quote 3050 to 3100 for a 175 in the Mashburn with a 24 inch barrel.

Is it one of those magical rounds like the 280 Ackley that have the "perfect" combination of something or other that hopeless gun cranks like to play with? I would sure hate to be at the Whitehorse, Yukon Airport with a 7mm Mashburn Super and realize that the bag with my ammo in it went to Calgary . (By the way, that actually happened to me, but my rifle was a garden variety 300 mag and I bought a box of ammo at the local hardware store).

Chet

Here is what Wrangler John asked recently:

" Why? What would the 7mm Mashburn Super Magnum do that an available 7mm magnum cartridge wouldn't? When looking at the ballistic tables all of the short 7mm magnums and the Remington and Weatherby 7mm magnums duplicate or better it. Other than the slightly longer neck, a dubious benefit, is it worth the hassle? Mashburn formed it out of .300 H&H brass (except the Long version which used full length brass). It would require similar tooling to my .375 Epstein Magnum formed on the .375 H&H, form and trim die, ream die, full length die. Necks should be annealed due to moving so much brass and forming the neck from the parent brass shoulder. I'm sure that forming the cases out of .300 Winchester brass would require similar tooling if the new neck will be moved into the old shoulder.

Now a days I could just buy a .375 Ruger and open a box of ammo or brass.

Is it worth the effort? "

My take on the old wildcat is that its just a fun old thing that came up with the recent Warren Page discussion.

It could headspace on its shoulder with judicuous handloading but its still a lot of trouble and with a belted case yet on a magnum action. As you and others have said there are similar commercial rounds.

The Mashburn has some 4+/- gr. more case capacity than the Weatherby and no more freebore than necessary. If one was jammed up in the Yukon or anywhere else without ammo you could shoot 7 mm Rem. since both headspace on the belt in theory. I have actually seen this at my local range with a fellow who inhireted his gfathers gun and didn't want to handload. I use Weatherby load data and a chrono for effortless loading. 3100 with a 175. Lots of horespower.

If you figure the capicity increase using JB's rule of thumb and your getting much over 1.5% increase in velocity you are sleeping in the street.

The current Hornady manual or at least my last Hornady manual shows the Weatherby running 3075 with a 175. I just use 3100 as a max. and let the chrono be my friend. 3100 fps. and a 175 is plenty. So is 3250 fps.+/- with a 160 gr.

How much longer is the Mashburn case than the Remington version? If you could safely and effectively use 7mm RM ammo in one, that would solve the lost ammo problem.

Chet

I wonder why it was never made into a commercial chambering? With Warren Page raving about it in field and Stream magazine it got as much attention as JOC gave the .270 in Sports Afield.

Was there something about it that would have been difficult to produce or chamber?

In the late 50's and early 60's everyone was worried about fitting everything into a 30-06 length actions from 03-A3's and surplus Mausers. The Mashburn works best with a .375 length action like the Rem 700 or Win 70 so the Mashburn was shortened a few .00's and became the 7 Rem. If the Rem is long throated and 160/175's loaded with the bullet bases at the neck base the difference is about 100 fps or 3000+/- vs 3100 with same pressure and bullet weight.

Look at the .300 Win and you have the same packaging issue and answer.

There is a good Mashburn cartridge diagram in Wolfe's big book of wildcats. Compare it to a Rem diagram and you will see that the Rem will work in the Mashburn. Not a great idea but in a jam it will work.

I had a 7mm Mashburn about 40 years ago. The MAJOR difference between the 7mm Mashburn and Weatherby cartridges is that the Mashburn cartridges were not pressure tested (just guesses from what I learned) nor SAAMI approved (no standards). The Mashburn did generate impressive performance, but at what pressures? I never did know and just went about stuffing powder into the case.

In the 50's,Page had the Mashburn rifle and loads pressure tested at Remington in his rifle..it apparently came through OK with velocities of 3050 with a 175 gr bullet,this in a 22" barrel,so Remington had the data in their lab.The load was 73 gr 4831...with some lots of that powder,Page had to drop a grain,as 4831 varied a bit lot to lot.


Chetaf if I wanted some straight scoop on the Mashburn I'd call Darcy....he has been loading for it and knows its' capabilities.

Bob Hagel wrote a great article on the Mashburn and does a comparison of the cartridge to the 7RM, and even to the 7mm/300 Weatherby.

Yeah people build Mashburns for the same reason they build 280AI's

Chet lost ammo is of course always a risk and if a guy tends to be a Murphy's Law pessimist,he is likely better off traveling with the garden variety cartridge that's available everywhere...in this regard you are even likely better off with a 7Rem Mag or 300 Winchester than any Weatherby chambering,as even that stuff can be rare in outback locations...

As to differences between the 7 Roy and the Mashburn,any honest discussion has to begin with the fact that all these various belted 7mm's are close to one another,and toss in the 7mmWSM and STW to further compound the problem....and as a 7mm RUM fan pointed out,it's the fastest of them all.....I note the differences with a 175 gr in the RUM from a 26" tube,over the Mashburn, amounts to about 100 fps...nevertheless, it IS faster across the board,albeit with powder charges in the high 80's tolow and mid 90's....

When comparing cartridges, we run gleefully for the loading manual,assuming (hoping) that our rifles will actually get the velocities quoted with the loads listed....sometimes this is true,and just as often it isn't.

I prefer a "boots on the ground method"(as many of us do),so over the years have made a habit of actually owning the calibers in question,loading for them and shooting them, instead of "guessing".

Along these lines I've had 2-3 7mmWSM's,more 7 Rem Mags than I can count (going back to the late 60's),a 7mm Dakota, a 7mm STW,and of course more recently, the Mashburn (a pal has another and we have done load development side by side).

This only qualifies me to comment on what I have seen;and that is, across the board the case with the most capacity "wins".....the smaller magnum 7's do well,but especially with the heavier bullets, if I am going to "bet" the cost of a custom or factory rifle on attaining a certain velocity level I want to achieve(for example,a 175 gr bullet at 3100 fps),I am not going to buy a smaller case in the hopes of loading it to the gills to get there...I beleive in running loads to trouble free ax...but won't stomp on a cartridge.

"Stomping" results in seeing things like Federal factory ammo for the 7mmWSM doing 3250 with a 160 gr bullet from two rifles,and leaving ejector slot marks in cases, and brass so swollen it could not be rechambered.The WSM behaved better at a hair over 3000 with the same bullets in my handloads...or the 7 Rem mag with the same bullet at 3050-3090 or so....I have learned to stop there with those cartridges.

The 7mm Dakota and the Mashburn,OTOH,both easily moved the 160 at 3200+ fps without a whimper,with good case life and a predictability I can live with ....this from two rifles.

Whether the benefits are worth the toil, trouble ,and inconvenience of the wildcat is strictly up to the owner..Just an observation for what it's worth

I have asked this question before, but is (was?) there more than one 7 Mashburn? Like in 'Regular' Mashburn and 'Super' Mashburn.

If there was more than one, what was the difference in them? I have read that one of the Mashburns used the .300 Win. Mag. necked down, and I have also read that one used the full length .300 H&H case, blown out.

They used the belted .300 H&H case in one configration or another, but does anyone know the differences, if there is any?

If you will go to PO Ackleys book you will find more old wildcats from the 50's and 60's than you can ever imagine. Art Mashburn had 2 belted 7 mm wildcats, both used .300 H&H brass. One was full length and would likely equate to a 7 mm STW today and the other used shortened brass with the shoulder pushed back. The shortened cartridge seemed to be a better balance of powder capacity and velocity production, hence the monicker "Super". When .300 Win brass came upon the scene it was easier to start with it as a base for case formation than to go the .300 H&H route with more work.

The shorter of the 2 varients is what Bob, Duber, and I use and we along with Bob Hagel, Warren Page, and Art Mashburn call it "Super".

Thanks, that explains it. I have a very old Speer loading manual that has data for a 7 MM Mashburn Super Magnum, but I have also seen reference on these forums to a 7 MM Mashburn. I was wondering if there was a difference.

Back in the early 60s, I wanted a 7 mm Mag. I had an FN Mauser commercial action and I was going to send it to Douglas to have a 7 MM barrel installed. I remember looking at the 7 MM Rem., the 7 MM Mashburn, and the 7 MM Wby. I choose the Wby., and I still have it. I don't remember why I choose the Wby.--it has been a long time ago, but that was my choice.

A friend shot an antelope with it, facing him, at a measured 304 yards. The bullet hit between the front legs and exited the left hip, dropping the antelope right there.

Bob,

What kind of velocity were you able to get with the STW with 160 and 175 grain bullets?

Thanks,
Chet

Chet I only worked with the 160's in the STW and velocities were in the 3200 fps range from a 26" M70 factory barrel.

Could I have gone faster? I don't know....maybe,but the rifle was long, heavy,and not what I want to lug around hunting.

Nevertheless it's obviously a good cartridge.

Bob would you run a sporter contour on a mash? All this talk has got my wheels spinning and lilja has a #3 1:10 in stock. I'd just need to find a donor....amongst all the RL components.

jr: Ours are #2 Kriegers, 9 twist.

I would think a #3 would be great! But I would wait and order the 9 twist. A 10 twist may work but I have never had one....others here may know....

IIRC back when the Mashburn started up and into the 60's before the 7RM, they had the 7mm Weatherby of course but early rifles were a 12 twist....they would not stabilize 160's.Some custom smiths made 7mm Weatherby's with a 10 twist that did work better....so maybe the 10 will work.

Hopefully someone who really knows will post up...I'm not sure.

I like the idea of a #2 better, you made it sould like you were using the magnum contours on a 24.

I think i'd be staying the the 140-150 range for pills so I figured the slower rate would work.

I'm thinking it should.....Terry from Oregon is running 150's at about 3300 IIRC....working from memory...Dober shoots 150 BT's in his but not sure of his vels.

I have been using #2's on 7 mags for quite awhile....make the rifle to be kind of a grown up 270.

...I try to keep them under 8#'s.This works well for me.

jr is your 7 RM a Rem 700?

If so, you can just punch it to Mashburn and you are GTG.No other changes required.Plenty of mag box to load to H&H length.Should feed fine.

I had a 284 Win with a 10 twist PacNor. It would stabilize bullets up to the 162 Hornady just fine. Never tried anything heavier.

At the increased velocities of the Mashburn I would have zero doubt that the 10 would work, splendidly.

Cripes, where's Dober on this?

Yeah, it's a 700 but my first rifle, took all my first animals with it. I might have a hard time tweaking it like that. Besides, I could always use another. That way i'll have small, medium and large (7x57, 7RM and 7 Mash).

There we go....Rick knows if a 10" twist will work.