Forming the 7MM Super Mashburn

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chuck nelson

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They are formed using 300 Win Mag cases and FL or form dies (I have both and run the cases unlubed through the form die then the FL die). Fire forming will take a bit of taper out of the cases and sharpen the shoulder angle.

L to R: 7MM Mashburn, 7MM Rem Mag, 7MM Mashburn, 300 Win Mag.

Maybe RickF will have something to add.

IMG_3191.jpg
 
chuck nelson said:
I'm building one.
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There are a number of factory rounds that will do the same thing. After I mucked around with wildcats and brass forming a bit, it's always been my personal choice to (mostly) use that which can be obtained via factory loadings, with no mussing around with forming brass, since nowadays whatever you want to do has been pretty much covered....

But the beauty of being a gunnut is to scratch whatever itch you may have, so if that's the case- let us know how it performs when it's done. :)
 
I guess you can squeak a wee bit more FPS out of this than a 7mm RM in a standard long action. I'd think I'd find a Magnum length action, build a STW and be done with it.
 
chuck nelson said:
Be done with what?
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Getting as much as possible from a .284. I guess there is always bigger and better (7mm RUM over a STW). I can see the appeal in upping the 7mm RM in a standard length action. Are the cases in the picture fireformed yet? If not how steep is the shoulder on a fully formed case?
 
cam1936 said:
Getting as much as possible from a .284. I guess there is always bigger and better (7mm RUM over a STW). I can see the appeal in upping the 7mm RM in a standard length action. Are the cases in the picture fireformed yet? If not how steep is the shoulder on a fully formed case?
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I want to hear more about the standard length action of the 7Rem v. the extra-long action required for the STW. What brand rifle are we talking about?
 
RickF said:
I want to hear more about the standard length action of the 7Rem v. the extra-long action required for the STW. What brand rifle are we talking about?
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Pretty much all brands. A STW has a 2.85" case, which is full 375 h&h length and requires a magnum length action.

A 7 RM is 2.5" and takes a .30-06 size standard length action.
 
cam1936 said:
Pretty much all brands. A STW has a 2.85" case, which is full 375 h&h length and requires a magnum length action.

A 7 RM is 2.5" and takes a .30-06 size standard length action.
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I'm prety sure RickF and Chuck are using Model 70's...is there anything else?

All "long action" Model 70 Classics are the same length,...remove the spacer from the rear of the 30-06/7 Rem Mag length mag box and you get 3.6"...same as the STW/H&H mag box.

The STW does have trouble reaching the lands and still fitting in a 3.6" box and even a Rem 700's 3.7" box...the Mashburn shouldn't have that issue,...as long as the throat is not overy long.


Imagine , playing with wildcats on that old obsolete belted case,....these two gun nuts are a couple of real throw back traditionalists,...they have guts....give 'er boys:D
 
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