case belt

[Nighthawk]

I have a question on the case belt. I was talking to my uncle and mentioned an unbelted magnum such as the 300 RUM and Tomahawk and he didn't know how that would work. He said something about a .22 caliber with a belt would blow off the bottom of the case without a belt. How would you go about making a case to handle extremely high pressure without blowing and or safety problems?

 

[Brent]

The belt is used to headspace the cartridge off of... nothing more. More problems are created using a belted cartridge than are solved, if enough shoulder is left in its design to headspace off of that is. The case is actually thinner near the edge of the belt than on non belted case designs FWIW. There's now way to size the belt in a standard die. The collet die Larry Willis makes to size the belt area is your best bet if you use the belted cases smaller than the 416 Rigby. I go non-belted from now on, and belted helps none as far as blowing the case head off, too much FL sizing, excessive headspace or partially unsupported case web and high psi will though. You have to understand what causes it in the first place, then everything falls into place from there.

[ 05-01-2003: Message edited by: Brent ]

 

[Nighthawk]

Thanks Brent.

 

[CatShooter]

Brent...

The history of the belted case is rather colourful.

Back in the beginning of this century, dangerous game was shot with double barreled rifles using rimmed cases (similar to the 45-90 and 50-140).
The two barrels were to allow a very fast second shot on a charging animal (Lion, Rhino, etc)... and also in case there was a failure of a firing pin or spring, cuz metalergy was in a primative state at that time.

When the Mauser "type" action was accepted as reliable enough for dangerous game, the rimed cartridges were not suitable for feeding through the magazines.

But because of the lack of standardazation of chamber dimentions, using a straight walled, rimless cartridge (Like the cylindrical '06x450) was impossible at the time, cuz the chamber length varied so much., that it would be possible to feed a round and have it be too far forward to fire, or extract.

So the belt was added by Holland & Holland to several new cartridges in their line, to be used in their brand new "African Magazine Express Rifles", and they worked very well.

The .375 H&H is still famous after some 100 years, and still suitable for taking the "Big five"... and the 300 H&H was a winning round, both in the field, and at Camp Perry well into the '60s, which ain't too shabby in performance.

After these H&H rounds were introduced, the "belted magnum" case became synonymous with "powerful" cartridges...
... so much so, that Roy Weatherby put a belt on their itty bitty .224 Weatherby, a round that was about the same as the Rem .222 Mag

(HA!)

Because of tight tolerances and standardization by SAAMI, the current belted rounds headspace on the shoulder (when there IS a shoulder), not the belt... especially after the first firing.

There are no other problems or concerns with reloading them, and special dies are totally un-necessary.

I own an English .375 H&H "African Magazine Express Rifle", and also a 300WM long range match rifle, and shoot both with no problems loading the cases with standard Redding dies. Cases last as long as regular "beltless" cases.

In the older conical chambered M70s, and Mausers, a good (and logical) argument can be made that the belt added some measure of needed extra strength because of lack of suport in that area of the chamber.

CatShooter.

[ 05-06-2003: Message edited by: CatShooter ]

 

[Brent]

Very interesting and edjucating, thanks Cat.

I have never had too much of a problem with belted cases but, I have noticed them get too tight after 5-7 loads and have no way to size the belt and just ahead of the belt down. I keep pretty good records on diameter in these areas and reduce loads enough to keep expansion "very" minimal there. One hot load shot a time or two is enough to create problems you can take care of with a non-belted but can't with a belted. My 416wby brass is pretty **** expensive, and 400gr A-Frames are good belt expanding offenders at the same pressure and velocity as the 400gr XLC on the Oehler 43 that doesn't do this at all... Could be the coating, but it was almost exactly the same with the non-coated X bullet too.

Pressure comes with 3-4 grains less powder in the A-Frame too, don't ask me why but, 111gr RL22 equals the 115gr X or XLC pressure and MV but give consistant increases in belt expansion after the initial forming, with the X bullets it is almost nothing, a few tenths is all. Just my experience.