Supposedly makes a cartridge more "efficient". Has there ever been any evidence presented to back up that claim?

none, but Roy did finally admit that it did make it a lot harder for gunsmiths in the old days to cut a reamer and copy the design. The other marketing "Trick" Wby used was buying barrels with the bore oversized a couple thousandths, and rifling only .001" deep. Along with a barrel length of 28-30". Most of the factories never mentioned that their MV data was derived from 28"+ either.

If you did not know, most gunsmiths in the old days did not buy reamers, they made them. A lot of designs were the builder's own, and it did not pay to buy a reamer unless you knew you could cut several chambers for customers. Most popular method was to cut what was called a "Single Flute" reamer. They would make a design, or copy one from a loaded round or fired case, in the shape of a cartridge, and cut it in half lengthwise. It was a very close copy, then the edge(s) were sharpened to final specs. It would usually last long enough, from what I was told, by people like Ackley and Buhmiller, to cut a chamber, and a set of dies. Seater first, then sharpen it and make the FL sizer.

A lot of the old guys, pre-1965 bench rest shooters/gunsmiths, would do something a bit different, shoot a match and win with their design, and have customers wanting the new design.

My favorite of all time, was an East Coaster that named his wildcat after himself. The .22 Marciante Blue Streak. It was a sharp shouldered take off from Harvey Donaldson's 219 Wasp. He was in a rush, ran his 219 factory Zipper brass thru his die, and left the necks FL 30-30 (parent case) Fl length instead of trimming them. He then cut a single flute reamer, re-chambered his barrel in this long-necked version, and won the match that weekend. The next week, everybody he built his standard on wanted the newest version.

So, no, there is not much, if any advantage to all that mumbo-jumbo about the Powell/Miller Freebore Venturified should design. The one-caliber plus freebore Weatherby employed is responsible for most of the observed velocity gains. Remember, in those days they got their numbers by estimating added velocity from drop tests. A friend's uncle had an OM 70 in 300 Magnum. He sent it to Wby for his improved design.

Test One: they would shoot the rifles on paper with factory ammunition, rechamber, then shoot it again with their hot loads. The bullet, as with any increase in velocity, would print higher on the target. They would measure the difference, and guess-timate the added velocity from the POI difference.

Test Two: They set up pendulum gongs at "X" distance and shoot. They used string, in many instances, to see how far the pendulum swung in inches. Then, rechamber, shoot their hot loads, and measure the distance the pendulum swung with the string. Surprise, the added velocity ='ed added ME, and the pendulum swung farther. Again, they would compare the difference and interpolate the data to guess-timate the velocity.

When the original chronographs, made by the Potter Company came out, and owners started checking actual load data against reports in the American Rifleman (which was the only source until after WWII) a lot of the numbers.

I was a kid at the end of that era (born in '49), but a Great-Uncle shot Scheutzen, and gravitated to Bench Rest about 1935.

Rich

Nice info , Rich.

quote:

When the original chronographs, made by the Potter Company came out, and owners started checking actual load data against reports in the American Rifleman (which was the only source until after WWII) a lot of the numbers.

When I got my first Chronograph it was kind of like when my friends told me there was no Santa Claus.

Interesting reading. Thanks

Roy Weatherby would probably been an excellent used car salesman too.

Cool information. I just bought a Magnetospeed and find it fascinating.

Also Weatherby's .240 is, in fact, nothing more than the .240 Holland and Holland with the shoulder blown out.

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o Weatherby's .240 is, in fact, nothing more than the .240 Holland and Holland

Boy H&H sure sounds better than WBY.

The .240 Holland & Holland Magnum (also known as the .240 Apex, .240 Belted Nitro Express, .240 Magnum Rimless, or .240 Super Express) developed in the 1920s. Roy was just a touch late.

I hadn't realised this RR until I was actively seeking to buy a .240 H & H bt worried about obtaining cases.

Looked at Cartridges of the World to see what might "do" and, low and behold, Weatherby's .240 was identical except for the shoulder style and its position!

So, by deduction, I worked out where he'd taken that from...

I always have to laugh about the Weatherby double radius shoulder.

Seems it came from a Winchester cartridge that was introduced in 1895

So nothing is new just recycled.

The 7x61 Sharpe and Hart, a belted magnum cartridge designed by the two respected American gentlemen and only factory produced by Norma, had a small sharply angled shoulder which was hard to distinguish from the double radius of the Weatherby cartridges. Also having a very similar shoulder was the 275 H&H belted cartridge.

The 7x61 cartridge has always been recognised as being a very efficient cartridge able to produce high velocities with minimal powder. I did read somewhere many years ago that this trait was attributable to the shoulder shape, as in all other respects the Sharpe and Hart cartridge was no different than any of the other belted magnums but it did seem to have an edge.

I chronographed the original Norma factory 160gr load in my Schultz and Larsen rifle back in 1988 and got 3040fps which was pretty close to the factory spec of 3100fps. My all time favourite load with the Sierra 160gr SPBT projectile and 59.0grs IMR4831 produced a very consistent 3000fps, a very deadly load on any of our game animals.

quote:

Originally posted by eagle27:
The 7x61 Sharpe and Hart, a belted magnum cartridge designed by the two respected American gentlemen and only factory produced by Norma, had a small sharply angled shoulder which was hard to distinguish from the double radius of the Weatherby cartridges.

The S&H shoulder in the cartridge diagrams I've seen has a regular angled shoulder of 44 degrees, not a radiused shoulder like the Weatherbys. http://stevespages.com/jpg/cd7x61sharpehart.jpg

Its shoulder is quite sharp, but not at all radiused. Regardless, neither the double radius nor the sharpness of the shoulder angle has any practical effect on velocity or efficiency. Test after test has demonstrated that it is total case capacity (or actually, chamber capacity since the case is elastic and expands to whatever size the chamber is) that determines the velocity/pressure of a given cartridge. This is often difficult to quantify with a small number of samples since other factors such as bore size, bore smoothness, and even rifling shape and pitch can alter pressure/velocity. But the bottom line is that whether a cartridge is three inches long or only an inch and a half long and whether it has a long, sloping shoulder or a radiused or sharp angled shoulder, it is going to do about the same thing with the same load if its internal volume is the same. (The "short magnum" series closes the velocity gap with the conventional magnums simply by being loaded to demonstrably higher pressures.)

quote:

The 7x61 Sharpe and Hart

Perfect capacity for the 7mm in "my opinion"

The 7x61S&H worked for me for many years as well. Great cartridge even if I no longer need the capabilities and have been very well served with the 7x57.

I agree the double radiused shoulder is a gimmick, but my 270 Weatherby shoots 150g Partitions at over 3200 fps chronographed. Its an old Mark V (made in Japan) with a 26" barrel I bought for $800 used several years ago. It's accurate too. A bit heavy for elk hunting, but a nice rifle all the same.

"Weatherby wonder tonic". Just saw this in another topic. Couldnt resist.

I also believe that the efficiency of the 7X61 S&h has more to do with its capacity than anything. It stands to reason. It is like you can load a 7mm Rm down to 280 velocities, but it will always require more powder than the smaller case to do so.. I would LOVE to have a 7X61!

quote:

Originally posted by Stonecreek:

quote:

Originally posted by eagle27:
The 7x61 Sharpe and Hart, a belted magnum cartridge designed by the two respected American gentlemen and only factory produced by Norma, had a small sharply angled shoulder which was hard to distinguish from the double radius of the Weatherby cartridges.

The S&H shoulder in the cartridge diagrams I've seen has a regular angled shoulder of 44 degrees, not a radiused shoulder like the Weatherbys. http://stevespages.com/jpg/cd7x61sharpehart.jpg

Its shoulder is quite sharp, but not at all radiused. Regardless, neither the double radius nor the sharpness of the shoulder angle has any practical effect on velocity or efficiency. Test after test has demonstrated that it is total case capacity (or actually, chamber capacity since the case is elastic and expands to whatever size the chamber is) that determines the velocity/pressure of a given cartridge. This is often difficult to quantify with a small number of samples since other factors such as bore size, bore smoothness, and even rifling shape and pitch can alter pressure/velocity. But the bottom line is that whether a cartridge is three inches long or only an inch and a half long and whether it has a long, sloping shoulder or a radiused or sharp angled shoulder, it is going to do about the same thing with the same load if its internal volume is the same. (The "short magnum" series closes the velocity gap with the conventional magnums simply by being loaded to demonstrably higher pressures.)

Just a correction, I said the 7x61 S&H had a sharply angled shoulder which was hard to distinguish from the Weatherby double radius. I didn't say the S&H actually had a double radius.

Here is the 7x61 S&H cartridge, pretty close to a double radius but not.