Belted Magnum Cases: A Myth Dispelled

Many tend to think the belt on belted magnums is to help the cartridges handle high pressure. In reality, the belt creates proper headspace in a rifle's chamber.

Many tend to think the belt on belted magnums is to help the cartridges handle high pressure. In reality, the belt creates proper headspace in a rifle’s chamber. Photo courtesy Massaro Media Group and JNJphotographics.

I love them. They captured my heart as a young man.

Wide bodied, with that sexy belt of brass just in front of the case head, and a name that inferred an unprecedented level of power: “Magnum.” I’d raise my eyebrows and prick up my ears like a German shepherd every time I read one of Col. Boddington’s articles where he highlighted one of the new magnum cases.

To my unknowing eyes, the cartridge that had that big belt of brass could withstand unearthly pressures; it just had to, because it was built so strong.

Well, time and education has revealed the truth of it all. That beautiful belt has nothing at all to do with strength; it serves to function as a means of headspacing. Allow me to rewind the clock 100 years or so.

The good gents at Holland & Holland had developed a high powered (for the day) .375” diameter cartridge. Not the .375 H&H Magnum we all know and love, but a cartridge called the “Veloplex.” As it didn’t quite fit the bill, they kept the bore diameter and revamped the case. What those proper British fellows were after was a cartridge that would offer the easy feeding attributes of those new fangled rimless cases, but still give the positive headspacing of the rimmed cartridges.

Rimmed cartridges didn’t require a shoulder for headspace, yet they don’t feed well from a box magazine rifle. Rimless cases need (generally speaking, there are exceptions) a shoulder for headspace. I’m not sure who the genius was at H&H that said (at least this is how I can vision it) “Why not put a small rim ahead of the rimless case head, and Bob’s your uncle, we’ve got the best of both worlds!”

The long and short of it is that the gentleman was onto something.

The .375 H&H Magnum, and its junior counterpart, the .300 H&H Magnum, both headspace off the belt, not off the shoulder. The very slight shoulder on the .375 H&H and the sloping shoulder of the .300 H&H are the features that give those cases the “smooth feeding” quality that proponents of those cartridges love so much. I believe the same could be said of the .416 Remington Magnum. The straight walled .458 Winchester Magnum and the .458 Lott are examples of cases that have no shoulder and also headspace off the belt.

The more familiar magnums, like the .300 Winchester Magnum, 7mm Remington Magnum, .338 Winchester Magnum and .300 Weatherby Magnum all headspace off the cartridge shoulder, and perform best when cases are resized to have that shoulder at the proper dimension. Most every other cartridge that features the H&H style belt will use the shoulder for headspace, and the belt on this style case is non-functional.

The same decade that saw the birth of the .375 H&H Magnum would bear witness to the release of the .404 Jeffery’s and the .416 Rigby. Although neither of these cases had the “Magnum” title, they certainly performed like one. The .416 Rigby has a very steep shoulder (almost 45 degrees) and has been used as the parent case for some of our modern magnum sweethearts: the .338 Lapua Magnum and .450 Rigby.

All three of those cases are beltless, and perform just fine. The .404 Jeff went on to be the platform for Remington’s Ultra Magnum series. Case wall were expanded to near parallel, and necked down to hold 7mm, .308”, .338” and .375” diameter bullets, and my buddy Bryce Towsley has a great wildcat based on this case necked to hold .358” bullets. The popular Winchester Short Magnum series would also be a beltless design.

The more familiar magnums, like the .300 Winchester Magnum, headspace off the cartridge shoulder, and perform best when cases are resized to have that shoulder at the proper dimension.

The more familiar magnums, like the above .300 Winchester Magnum, headspace off the cartridge shoulder, and perform best when cases are resized to have that shoulder at the proper dimension. Photo courtesy Massaro Media Group and JNJphotographics.

All the beltless cases are, in some theories, more “inherently accurate.” I can’t verify that theory, as I’ve seen some incredible accuracy from both kinds of cases.

On the positive side, if you shoot a belted magnum case, can create brass from other cases based on the H&H platform. On the downside, there is some case stretching that occurs just in front of the belt, which may shorten case life.

If you’re picking out a new magnum cartridge, don’t feel that you must have that belt. But I’m not getting rid of my .300 Winchester, .375 H&H or .416 Remington any time soon!

 

 

 

 


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One thought on “Belted Magnum Cases: A Myth Dispelled

  1. vishnu

    “The more familiar magnums, like the .300 Winchester Magnum, 7mm Remington Magnum, .338 Winchester Magnum and .300 Weatherby Magnum all headspace off the cartridge shoulder…Most every other cartridge that features the H&H style belt will use the shoulder for headspace, and the belt on this style case is non-functional.” So why bother with the belt? I’m thinking “marketing”.

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