7mm Sherman Short Mag?

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350 Mag

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Ran across this and thought it was worth a share.

He claims he can out-perform 7mm SAUM.....and do it with less pressure...out of a smaller case?

3200 fps 168 berger.
over 3000 fps 180 berger

https://www.longrangehunting.com/threads/7-mm-sherman-shortmag-vs-7-saum.155921/



It has a conventional throat. The case is more efficient with the very short burning column, straight wall design and 40 degree shoulder. Also, because of the distance from the shoulder/neck jct. being much shorter than a SAUM, it allows for a much longer throat so that the useable case capacity is not taken up by the bullet. The case design also does allow for the pressure to be distributed a little better without stretching as easily. I wil say that SOME of the velocities listed probably did have some pretty excessive oressure, but it will outrun a SAUM with equal pressures .........Rich
p.s. If you long throated a SAUM, you could get closer to the SS velocity but that defeats the whole purpose of having a short action. You would have to run it in a long action to gain the benefit, which some people do.
"....
 
I Have a 6.5 Sherman. Very impressive performance with a 270 Win as the parent case. Drives a 140 Berger at 3339 fps out of a 28" Hart using N570. Rich's designs work as advertised.
 
My 6.5 Sherman is based on the 270 Win. His SS based designs are off the SAUM I believe, for short action builds. You guys can laugh all you want, but there is a huge following of the Sherman based cartridges. Is it a perfect design; no but what is? I really like mine but the brass prep takes a bit long. As far as the over pressure jokes go, you can run any gun you want over pressure and make speed. So I don't see why you don't believe that these loads are safe when there is hundreds if not thousands of guys shooting the Shermans.
 
beeman2 said:
My 6.5 Sherman is based on the 270 Win. His SS based designs are off the SAUM I believe, for short action builds. You guys can laugh all you want, but there is a huge following of the Sherman based cartridges. Is it a perfect design; no but what is? I really like mine but the brass prep takes a bit long. As far as the over pressure jokes go, you can run any gun you want over pressure and make speed. So I don't see why you don't believe that these loads are safe when there is hundreds if not thousands of guys shooting the Shermans.
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I think people are "skeptical" is because he claims something out of the norm....

Smaller capacity wildcat cases usually don't exceed velocity of parent case?

The numbers just do not add up....
 
beeman2 said:
My 6.5 Sherman is based on the 270 Win. His SS based designs are off the SAUM I believe, for short action builds. You guys can laugh all you want, but there is a huge following of the Sherman based cartridges. Is it a perfect design; no but what is? I really like mine but the brass prep takes a bit long. As far as the over pressure jokes go, you can run any gun you want over pressure and make speed. So I don't see why you don't believe that these loads are safe when there is hundreds if not thousands of guys shooting the Shermans.
Click to expand...

I don't doubt that you and others are "getting" 3389 fps with a 140 gr bullet with a 28" barrel out of the 6.5 Sherman. It's a case that is a maximally improved 6.5-06, much like the old-time 6.5-06 AI and 6.5 Gibbs, + 1-2 grains - which is "noise" really. I also believe that your gun didn't blow up, and that you might get more than one firing before the primer pocket can no longer hold a primer. So no-ones calling anyone a liar.

It all comes down to the various claims about pressure, i.e. that a few thou here and a few degrees there defies the laws of physics. Those numbers are about 150 fps faster than a much larger 264 Win Mag at 60K psi, and beat out the 7mm Rem Mag by almost as much, so you know you're running well above that pressure-wise. That's almost what I can eke out of my 6.5-300 Win Mag with 84.0 grs of US869.

There's a reason why the designer of these rounds has not had them pressure-tested in a reputable independent lab - they're running in the 75K psi range. Why doesn't he just do that and shut us up?
 
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I know that going by heavy bolt lift and marks on the brass isn’t fool proof. My 140 Berger load showed none of these pressure signs. I ran my brass at 5 loadings before primer pockets loosened, which I think is pretty good. I’m no expert on pressure but with 5 loadings and no other pressure signs I feel it was a max load but also safe. I know it sounds crazy that a 270 parent case can run with a 264 Win Mag and not far off a 26 Nosler. This winter I plan on developing a load with the 147 ELD-M. Some guys also say my 6.5x47 shouldn’t be able to run a 130 Berger at almost 3000 fps either. But I trust Travis at RBROS who built the rifle. He assured me I was not at max with the load he developed for me in this particular rifle. I would like to see a lab verify pressures in the Sherman as well. It would be very interesting.
 
There is ways to gain more velocity like running a lot longer throat/ proper freebore for the longer vld bullets. Usually when your doing that it forces you to run your rifle as a single shot because of the extra length. The other option is running a stepped throat on your reamer it helps to relieve preasure so you can run more powder in your case for faster velocity. The guys in the states doing it claim 150-200fps gain. You can read more about it online if your interested. Thats one reason i wont give out load data unless the gun was chambered with the same reamer as mine.
 
mudpro said:
There is ways to gain more velocity like running a lot longer throat/ proper freebore for the longer vld bullets. Usually when your doing that it forces you to run your rifle as a single shot because of the extra length. The other option is running a stepped throat on your reamer it helps to relieve preasure so you can run more powder in your case for faster velocity. The guys in the states doing it claim 150-200fps gain. You can read more about it online if your interested. Thats one reason i wont give out load data unless the gun was chambered with the same reamer as mine.
Click to expand...

All that an enlarged throat does it increase the effective case capacity, by allowing the bullet to be seated out farther, or by allowing it a longer runup to the rifling which has the same effect, although that often has a negative effect on accuracy. Even in single-shot mode where mag length is not an issue (and in most cases it is), you're not likely to increase the case capacity by more than 5% or so, a common example being running a 6.5-284 in a Standard (30-06 length) action. That should account for 50-75 fps at the same pressure, but it's easy to pump it up to 200 fps if you're relying on subjective "pressure signs", the reliable ones being evident only at very high pressures.

The only point I've tried to make is that increased MV's can only be produced by increasing pressure, and/or increasing case capacity so that more of an appropriate powder can be added. That's what the "Laws of Physics" comments are about.

I remain open to accepting the various arguments put forth that the case and chamber shape can have as dramatic an effect as claimed, but all it will take are pressure tests in a lab, and it looks like that isn't going to happen.
 
I am bumping this up...

Any SS Mag users care to chime in on how the brass is holding up on these "magic" case designs?

I do not want to insult the owner/designer or potentially harm his business by commenting on his threads on LRH.

Brass life?

Brass feeding from magazine with such a sharp shoulder.

To date no one has done any type of pressure testing even bother with Pressure trace?

Here is latest comments by Rich.

"People often ask what pressure we're running and the truth is, I don't know! The question I get a lot is "how can you shorten a parent case and make it shoot faster"? Glad you asked! ,
(1)There is no loss of capacity in the SS case vs the saum. Even though it is considerably shorter, with the taper blown out and the shoulder sharpened, the capacity is nearly identical. (2)Because it is far shorter, the bullet can be seated out into the neck so that useable capacity is MORE that the Saum. (3) the shorter burning column and 40 degree shoulder make the SS more efficient getting more out of the charge. (4) with low body taper, the pressure is distributed better throughout the chamber (less bolt thrust) this allows higher operating pressure without destroying brass. SS shooters will vouch that brass lasts longer at higher velocities than the Saum will reach
All these things are exactly why the SS was developed. To be the best performing cartridge available under 3" coal. You can get close to SS velocity with a saum, but you have to have a 3.1" coal to do it, and even then, you will likely come up a little short. I'm sure there are people who load hot, as with any cartridge, but the 7ss isn't running 3000' with a 180 vld by running dangerous pressure when the brass is lasting double digit loading! The skeptics should try it and see for themselves!"

Still have a hard time getting my head around the claims he can drive a 180 Berger into the 3000's easily and do it using less powder and pressure than a 7mm Saum????

All of course without laboratory tests....
 
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