Forming the 7MM Super Mashburn

Quote:
Originally Posted by todbartell
I bet it will kill something, but only if you wear a moose medallion around your neck when hunting

Emits special powers
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Sooo...do you boys back east wear one during the whopping long 3 day moose season? ;) I think having a rifle chambered in 7mm Mashburn Magnum has a KOOLNESS factor unavailable with run-of-the-mill factory chamberings and proudly screams out..."I AM a Gunnut" :cool:
 
BC Bigbore said:
Sooo...do you boys back east wear one during the whopping long 3 day moose season? ;)
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I'd need to wear the moose trivet for good luck just to GET a moose licence here. :D

BC Bigbore said:
I think having a rifle chambered in 7mm Mashburn Magnum has a KOOLNESS factor unavailable with run-of-the-mill factory chamberings and proudly screams out..."I AM a Gunnut" :cool:
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I couldn't agree more with that! It does say "KOOL". I like off beat chamberings as much as the next gunnut.

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Cam, funning you a bit. Pretty much all modern actions excluding the Ruger 77 are magnum length actions. You can put a block in the rear of the mag well and call it 30-06 length, but the action is capable of taking the full length cartridges. M70, M700, Savage, you name it.

Re why not the STW, as Rick N intimated it comes down to among other things throating. The STW is a tight fit in the normal actions. The 300 Win case (ala Mashburn) provides a longer neck which allows seating depths with different bullet weights/lengths out to the leade assuming an intelligent throat on the reamer.

The Mashburn comes within 50-75 fps of the STW, but does it in a 24" barrel with a fair bit less powder. This isn't about the fastest, it's about what a few people have decided to be the best design when capacity, potential velocity, barrel length, barrel life and accuracy tractability are considered.
 
RickF said:
Cam, funning you a bit. Pretty much all modern actions excluding the Ruger 77 are magnum length actions. You can put a block in the rear of the mag well and call it 30-06 length, but the action is capable of taking the full length cartridges. M70, M700, Savage, you name it.

Re why not the STW, as Rick N intimated it comes down to among other things throating. The STW is a tight fit in the normal actions. The 300 Win case (ala Mashburn) provides a longer neck which allows seating depths with different bullet weights/lengths out to the leade assuming an intelligent throat on the reamer.

The Mashburn comes within 50-75 fps of the STW, but does it in a 24" barrel with a fair bit less powder. This isn't about the fastest, it's about what a few people have decided to be the best design when capacity, potential velocity, barrel length, barrel life and accuracy tractability are considered.
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Isn't every cartridge a balance of pros and cons? Don't get me wrong I'm not hating on his build, in fact I expressed curiosity on the final shoulder angle the brass; which still goes unanserwed. I think this is indeed a good build. News to me that a 700 can fit a .375 length case, I've only looked at builds based off a m77, M 98 and SA Rem 700.
 
I haven't got the specs in front of me, but the shoulder angle is I think about 28 degrees.

The 300Win case is blown out to a bit less taper as well.

The best part of the cartridge is the nice long neck to allow seating lighter bullets out to the throat, and the fact that it comfortably gives the velocities that the 7Rem was supposed to. Namely 3200+ with a 160, and 3050-3075 with a 175. This in a 24" barrel.
 
anyone bother to compare case capacity ?

the mashburn case and the 7mm weatheryby case are so close to the same size that a person should easily be able to interchange reloading information between the two with one caveat .....

the weatherby round will be free bored ,
meaning ; that if it's the loading inforamtion was used in a non free bored chamber , that info could be on the hot side .

with chamber pressure be equal , barrel length being the same , the mashburn and the weatherby rounds are dam near twins .
 
The Mashburn is about 4 grains larger than the 7Rem.

The Wby and MSM are damned near twins, thanks to the freebore and Weatherbys propensity to load to higher pressures than some consider prudent.

Loaded to similar pressures and with like barrel lengths, the Mashburn will outrun the Wby by close to 100 fps.
 
Sorry, didn't see the shoulder angle question.

IMG_3199.jpg
 
RickF said:
The Mashburn is about 4 grains larger than the 7Rem.

The Wby and MSM are damned near twins, thanks to the freebore and Weatherbys propensity to load to higher pressures than some consider prudent.

Loaded to similar pressures and with like barrel lengths, the Mashburn will outrun the Wby by close to 100 fps.
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i pulled my info from the barnes #2 reloading manual , the weatherby case is about 5 grains of water larger than the remington mag case .







the 300 mag case ( which the mashburn is based on ) is roughly 2 grains of water larger than the weatherby case .

i have seen case capacity variances from different manufactures very close to the difference bewteen these 2 cases .




according to your own info of the mashburn case being 4 grains of water bigger than the remington case , this would make the weatherby case 1 grain of water bigger ....................

and again i say they are virtual twins


btw on a side note , the stw case is about 17 grains of water larger than the remington mag case ...... 13 grains of water bigger than the masburn case


finally found the web page i was looking for ......

http://www.chuckhawks.com/rifle_case_capacity.htm
 
Other manuals show the 7Rem case larger than the Wby.

I stated above what the MSM is comfortably capable of doing.

And if we are talking 150 fps or less, then the 7Rem, 7Wby, 7MSM and the 7STW are all virtual twins. Pick the one that blows your hair back and carry on!


Nice photo. You work for fire protection?
 
I've pushed 3233 fps sub-moa on an STW with a 180 grain lead, while seated to a depth that you can use the internal mag box on a Sako. I fail to see an upside to the Mashburn but without any results from the build it is fairly tough. I'm definitely interested so keep posting the build updates!
 
If ever there were an answer to a question nobody ever asked, I think this cartridge is it.

But hey, the great thing about personal choice is that you can fill your boots with whatever you like - so good on ya for experimenting.

All I see is a rifle hard to find brass for, shooting virtually identically to the 7RM which you can't spit without finding in the most back-woods of gun stores.

-M
 
Doc M said:
If ever there were an answer to a question nobody ever asked, I think this cartridge is it.

But hey, the great thing about personal choice is that you can fill your boots with whatever you like - so good on ya for experimenting.

All I see is a rifle hard to find brass for, shooting virtually identically to the 7RM which you can't spit without finding in the most back-woods of gun stores.

-M
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How is it hard to find brass for again?
 
Ok, so not to defend anyone elses bandwagon here, but in all ways that a cartridge is good, the Mashburn is heads and tails above the Remington Magnum. First, it is a decade older in conception, it has a longer neck, more case capacity, and fits the same damn action. Oh, and it was the answer to a question asked in the 40's: people wanted a cartridge that was faster than the .270, and hit harder than a 30-06, and the Super Mashburn was it.
Frankly, quite a few of us would piss into the wind before we would use factory ammo anyway, so sizing down some oh so hard to find 300 Winchester brass is really a matter of watching a sitcom and doing it.
Lots of the people crapping on this idea would likely crap themsleves if they could get a '67 Vette or a '69 Camaro Convertable, and forget that a new WRX is far faster, and handles better, and easier to get parts for. Its called "nostalgia".
So come up with a real reason not to do it. John Nolser (RIP) and Bob Nosler both prefer(ed) the Mashburn over the Remington, so it shows you that some people are starting with good company.
 
Who cares if it duplicates another cartridge, it's all part of being a gun nut.
I've got 6 different 257's.

I have a couple of Bob Hagel's books and he was a big fan of the Mashburn.

Looking forward to a range report.
 
chuck nelson said:
How is it hard to find brass for again?
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Send me a box of FACTORY 7MSM in the mail and I'll apologize.

No forming, no screwing around - just find me some factory loads, send 'em to me, and I'll apologize.

I love reloading as much as the next guy, but the practicality factor isn't weighing in on the side of the MSM.

IMO, the availability of common factory cartridges that can perform just as well (or within damn close spitting distance) of this loading make it not worth the hassle.

WITH THAT SAID...

... if you like playing with it, that's your prerogative - and more power to you! :)

-M
 
Just one more thought. A few guys in favour of, and a lot against, this cartridge.

Yes, I am building one. And I don't give a tinkers damn what anyone else thinks. ;) I build rifles to please me, not a bunch of strangers on the net.

Factory ammo availability? Good grief.
 
here is a thought , if like most belted magnums , there is the option of either headspacing on the belt , or the shoulder .........

so is there any reason why 7mm weatherby or even 7mm remington could not be used in the mashburn chamber , fireforming the brass ?
the neck will be on the short side after wards .......

or is this a case of asking the brass to stretch too much ?
 
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