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Reloading Berger Bullets


7mm mashburn super magnum

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Unread 01-27-2008, 08:03 PM
Bronze Member
Join Date: Nov 2007
Posts: 72
7mm mashburn super magnum

Is the 7mm mashburn the same thing as a 7mm-300win I've asked other questions before but don't get much is there a reason why this isn't a popular caliber if anyone has any info it would be appreciated like were to get dies how to form cases were I can get my rifle rechambers and no I don't want an stw or dakota thanks for nay help
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Unread 01-27-2008, 08:24 PM
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Join Date: Jul 2002
Posts: 2,855
I think it may be a bit bigger than the Win mag case ,I'm wanting to say that its based off of the blown out 300H&H case , similer to the 7STW. I haighly doubt that their will e enough diferance in performance to warent the cost of special ordered dies and reamer.

The 300 win mag case necked down to 7mm would be a good one , I think it would run realy close to the STW especialy if you use Lapua brass , if you were Ackley improve it then you would likely bea the STW and do so with a shorter OAL.

The 300 mag Lapua brass is awsome , at $1.50 a case it better be , but its as good maybe tougher than their 308 brass.
Si Vis Pacem Parabellum
Molon Labe
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Unread 01-27-2008, 08:54 PM
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Join Date: Jan 2008
Location: USA
Posts: 72
case length?

The 7mm Mashburn Super Magnum is based on a shortened/necked-down/blownout .300 H&H case, with the case length being 2.630", according to P.O. Ackley Handbook #1. Velocity for a 160 gr bullet was around 3200FPS. There were several other calibers based upon this length.

The .300 Win. Mag. case comes-in at 2.620".

Not much difference between the 2 cases in length.

Top loads in a 7MM Weatherby w/160 grainer is approaching 3200FPS.
Top loads in a 7STW approach 3200FPS w/160 gr.

The not-so-popular "7MM Mashburn Magnum Long", different from any of the other 7s, used the .300 H&H case full-length, 2.850". Loads with a 160 gr. bullet duplicate the 7MM Weatherby Magnum velocities. Of course, powder selection back in those days was not as it is these days, so different velocities may be attained when using more modern powders.

Best of luck to ya,

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Unread 01-28-2008, 10:37 AM
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Join Date: Nov 2007
Posts: 72
thats kinda what my plan was just can't find much info
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Unread 02-01-2008, 11:26 AM
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Join Date: Jun 2006
Posts: 163
gun writer Bob Hagel used a 7 msm alot and theres alot of stories about it in some of his books.
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Unread 02-01-2008, 03:49 PM
Bronze Member
Join Date: Nov 2007
Posts: 72
I am wondering if it is worth it or not what i wanted to do was have it set so I could load 180 bergers to the base of the neck and at that length the bullet woud be .025 into the lands and then i could adjust for accuracy and i figured i could get some decent velocity out if it the only down fall would be it would most likely be a single shot but with good lapua brass I should be pretty close to equaling the stw i think. sorry about the long post
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Unread 02-03-2008, 01:25 AM
Junior Member
Join Date: Feb 2008
Posts: 14
I used a 7mm super mashburn magnum.

I HAD A MASHBURM BUILT IN 1966.SHOT THE RIFLE FOR THIRTY YEARS AND WORE THE THROAT OUT.REBARRELED TO 7MM REM MAG.I STILL HAVE THE FORM DIE AND RELOADING DIES {rcbs}.also have loading data from art mashburm .brass can easlily be formed from 300 win mag.e mail me if you want any more info or dies.PS it shot 160 nosler parition at 3200 fps
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