Unknown ( to me) WILDCAT cartridge


Just received the cartridge on the left ( the bullet is not the original one as I have the fired case only) , based on the 240 Weatherby magnum with a sharp shoulder , compared to the standard double radius shoulder

Shoulder diameter is the same ( .435") and so is the body length

On the right is a standard 240 Weatherby

The cartridge on the left is unknown to me .Any help ?




I assume it’s a 240 WBY case? Fire-forming WBY cartridges to the more conventional shoulder is fairly common among competition shooters. It allows for more precise headspace control (shoulder-bumping). The WBY double radius shoulder was strictly a sales gimmick and there is no ballistic advantage or disadvantage to it.

Interestingly I have a 220 WBY Rocket (a wildcat) that has been changed from a conventional shoulder to the double radius. Why? Since when do wildcatters need a reason.

As for a name to your cartridge, it’s whatever you want to call it, I suppose.



Yes,it is a fireformed 240 WM case


Ladies and Lords…the 240 Gimmick



I like it.

Or you could call it the 6mm Ackley Belted Express because that’s what he (Ackley) called it before WBY brought it out with the double shoulder.



So I am to assume the 240 WBY Mag and the 6mm Ackley Belted express are the same round? Vic



I think the original Ackley had a 30 degree shoulder whereas the one Pivi showed looks more like 35 degrees or so. Not enough to make it ballistically different.

For those who don’t know, the Ackley Express cartridges were made by swaging down a 30-06 case to make it belted. Why they went thru all that work is beyond me, and I’m a wildcatter at heart. There were several of them in different lengths and in different calibers. At one time Nonte/Taylor made basic cases to sell. I have a bunch of different ones (I’d have to count them) and probably a photo too. I’d post the photo if I could get Photobucket to work.




But wouldn’t the expanding gases get all caught up and just sit there on those sharp corners without the double radius super duper venturi?..

Roy couldn’t have been into the added expense of making chambering reamers and case forming just for a sales pitch, now could he? Or maybe he just needed justification of the belted cases as headspacing wasn’t gonna happen very well otherwise… (smiley thingy)




Roy was a businessman and salesman in addition to being a shooter and hunter.

I found this one photo that shows some of the Ackley Express cartridges.




And a great businessman at that. Few people who have endeavored into the firearms marketplace could hold a candle to what he accomplished over the years he made the Weatherby brand famous. There are few things that are as distinct in my memory as those lucite blocks holding a selection of the Weathery line of cartridges when I think back to my younger years of collecting. The boxes of cartridges with the pictures of critters on them you could hunt with the things were the coolest on the shelf by far. The “red” vs. “green” guys always went tit fer tat. Roy took it well beyond.

Ackley Express vs. Ackley Improved being the less extreme shoulder angles?




You are correct about Roy. Most do not realize how many times he was broke and on the verge of bankruptcy and how the Weatherby line of rifles and cartridges almost never were.

The “Express” moniker was given to the belted Ackley cartridges. “Ackley Improved” has come to mean a factory case improved by increasing the shoulder angle to 40 degrees. What most people do not realize is that Ackley hisself preferred a lesser angle and you will find many Ackley wildcats and Improved cases with 30 degree (or less) shoulder angles. There are probably more “Ackley” cartridges that he had nothing whatsoever to do with than there are those that he developed and promoted. He had a big ego but never tried to take credit when it wasn’t his.



I calculated the shoulder angle using trygonometry , and considering the shoulder as a right -angled triangle.

That angle should be of 29 -30° ( I obtained 0.82 as the value of the opposite angle sine , which corresponds to 61.20°.
So 180 ° - 90° - 61.20° = 28.8 °)



Did you use trigonometry or geometry? I never could grasp the difference between the two, no matter how hard my teachers tried to get into my head.

If you are rich you can buy an optical comparator which is what the big kids use to measure angles on 3D items such as a cartridge case. But, you have a poor man’s comparator sitting right in front of you. Take a good, high resolution photo of the cartridge at a 90 degree angle to the shoulder area. Print it out several times actual size. Then with a straight edge and a protractor you can come pretty darn close to the shoulder angle.

Also, that way does not hurt your brain as much as trigonometry (or is it geometry???)



Ray,I’d say that trigonometry is a part of Geometry , since it is the science that studies angles ,not only for "practical " problems,such as rectangles,triangles etc,but also for functions that can be represented into a geometrical form .



Now I understand - NOT!

Don’t forget, it’s a wildcat. While the designer may have specified a 30 degree shoulder (or any other angle) the actual reamer dimensions will only be as accurate as the reamer grinder makes them. The older the cartridge the more unlikely the chance of the angle being exact. Today’s reamers are made by computer-like grinders and are more likely to be precise. In olden days, the reamer maker probably used the compound cross slide on his lathe and it could have been off a couple of thousandths in both directions.



I have resumed this thread since a friend of mine gave me some 240 Weatherby case samples fired in his Weatherby-Sauer rifle.

Well, all those cases have the straight shoulder, not the typical rounded one. The rifle was factory chambered and never modified. So I can assume that it’s simply a wrong chambering work