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Smallest Viable Magnum Cartridge?

.243 Wssm. Shoots 115 DTac over 3100. 41.5 - 42.0 H4350.
Truly a cartridge before its time.

I've wondered if you couldn't take a 6.5 PRC and bump the shoulders a good bit as you neck it down and have something like a "super BR" of sorts. I know the straight neck down has been done before, but it seems that it's just a bit too much. 60gr or so behind a 6mm just seems excessive and inefficient. I was thinking that if you had similar case capacity as a 6 creed, but with shorter and fatter geometry due to the magnum boltface, you could produce a slightly larger scale model of the 6BR case, albeit with a 6mm bullet still.

The idea would be case capacity about like a 6 creed or .243, but with the larger magnum OD that might permit a little faster burn that helps barrel life and might produce better MV and less recoil from a given charge-- all the kinds of benefits touted when the WSMs were initially launched.

If I ever got the courage/desire to explore a wildcat, it would mostly likely be of this kind. A 35 degree PRC case necked to 6mm with capacity about equal to a 243AI. Should have similar OALs to a 6mm creed but with the larger OD case and a bit steeper shoulder to help with brass stability when going so overbore.
 
That's the problem with marketing. Doug Wesson named the 357 magnum after a champagne bottle.
To me I look at pressure ratings. The 243 is 60,000 PSI and the 6mm Remington is 65,000 PSI so the 6MM could be considered a magnum 6MM. It certainly produces higher velocities if you give it the barrel.
The 243 is as overbore as a 7mm Rem Mag, Id say it and the 6Rem are verifiable magnum class rounds. However Neither one is worth a wet fart in a .532 bolt face!!! As far as the actual question I dont know! The WSSM dont have much appeal. The WSM are worth a look
 
Truly a cartridge before its time.

I've wondered if you couldn't take a 6.5 PRC and bump the shoulders a good bit as you neck it down and have something like a "super BR" of sorts. I know the straight neck down has been done before, but it seems that it's just a bit too much. 60gr or so behind a 6mm just seems excessive and inefficient. I was thinking that if you had similar case capacity as a 6 creed, but with shorter and fatter geometry due to the magnum boltface, you could produce a slightly larger scale model of the 6BR case, albeit with a 6mm bullet still.

The idea would be case capacity about like a 6 creed or .243, but with the larger magnum OD that might permit a little faster burn that helps barrel life and might produce better MV and less recoil from a given charge-- all the kinds of benefits touted when the WSMs were initially launched.

If I ever got the courage/desire to explore a wildcat, it would mostly likely be of this kind. A 35 degree PRC case necked to 6mm with capacity about equal to a 243AI. Should have similar OALs to a 6mm creed but with the larger OD case and a bit steeper shoulder to help with brass stability when going so overbore.
It's relatively easy to take a shoulder and move it inwards, as we are usually doing the opposite. A little brass play and I'm sure you could come up with a size easy to accomplish narrowing the PRC shoulder .495" or so. *
 
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If you have ever read anything by Jack O'Connor you should know the .270 Winchester is the world's best non-belted magnum.
Ol’ Jack and his opinions... Imagine if he’d been paid off by Hornady when the 6.5 CM came out...

Surprised the 222 Rem Mag and 204 Ruger haven’t been mentioned, yet. There is also the commercially available .223 WSSM, which would satisfy those with Little Boltface Syndrome.
 

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