Note: This is not the 300 Ackley Improved Magnum cartridge.... yes the work of Ackley did influence this project, but it is not in any way a design done by Ackley. The 300 Ackley Magnum cartridge is not able to meet all the criteria that was needed for this project.
What you are about to read is an article on a project that started with me just tinkering on the computer trying to see what I could come up with to help some shooters get a little more from their hunting rifles.
Everyone seems to love the 300 magnum rifles that have become as popular as the venerable old .30-06, and there have been many around the region that have taken the 300 Winchester Magnum to heart.To me the 300 Winchester Magnum is a great cartridge, but gives me a headache every time I shoot one of the rifles chambered for the large magnum.
It is no doubt more than enough cartridge to handle anything in Kentucky.
I have heard several speculate that a little more power or longer neck the 300 Winchester Magnum would shoot a great deal better. They state that the neck is too short to align well, and that more powder will increase the velocity to allow for flatter trajectory thus matching the 300 Weatherby performance.
To me you put a 26" barrel on a 300 Winchester Magnum with free bore then you would match the Weatherby. I hear many say that they would love a little more power to reach even further out to touch a target, that the other 300 magnums are too much recoil due to
either too small a rifle as with the 300WSM,
too much powder as with the 300 Remington Ultra Magnum.
So I began playing around with the idea of a cartridge that was based on the 300 Win Mag case and that wouldn't be too complicated for a hunter on a budget to upgrade a rifle they already owned. When asking around I also discovered that some people that use tactical rifles chambered in 300 Winchester Magnum kind of wished that they could have a shorter barrel on their rifle. So now that is a factor in the design of this cartridge upgrade.
So the task at this time was to find an upgrade to the 300 Winchester Magnum cartridge that would give the full velocity of the cartridge in a short 20" barrel, give those with 24" hunting barrels a little more bang for their buck, without being too costly to upgrade their rifle, and without over dosing the shooter with way more recoil than most can handle.
My mind instantly went to the work of P.O. Ackley and his family of improved cartridges where he took out the case taper, and sharpened the shoulder. I decided that I would let this be my inspiration for my wildcat, and see what I could come up with on the computer.
First I looked at the shoulder of the 300 Winchester Magnum which is formed to a 25 degree angle. Ackley used a 40 degree angle on many of his improved cartridges, but on this one to me that would be far too sharp for a cartridge as long as the 300 Winchester Magnum so I decided to split the difference and go with a 35 degree angle on the shoulder. This allowed for reliable function as well as more powder, so next I moved to the taper of the parent case changing it slightly to allow more case capacity. I kept tinkering until I had a cartridge designed that to me was just what the hunters ordered - a cartridge that would offer them just a little more power without them having to buy a new barrel or a new rifle to own. They would just have to have a gunsmith rent the reamer then re-cut their rifles chamber a little.
Please understand exactly what this project is all about not a revolutionary new super cartridge, but an upgrade. This cartridge would allow for a shooter to get more out of that shorter barrel as there will be more powder behind the projectile. Giving a tactical/light hunting rifle with a short 20" - 22" barrel the same performance as one with a longer 24" barrel. It wouldn't be a drastic increase in powder as to cause too much recoil, and seeing that only the cartridge shoulder, and taper was changed it wouldn't cost much to upgrade a rifle, and cases should/could be fire formed in the new chamber. The overall length, bore, and neck would all stay the same on the upper part of the case in the shoulder area would be different.
Next I wanted to check the SAAMI pressure chart to see what room I had to work with in regards to this important factor in ammunition. The max for a 300 Winchester Magnum is 64,000 psi, and most 300 Winchester Magnum loads fall within a range of 45,100 psi to 63,526 psi
according to my copy of Modern Reloading by Richard Lee. As far as I watch what powder I use I should have more than enough room to play with when I get to working up a load for this cartridge as the changes to the case to allow more capacity are not that big. Remember we are not just shoving more powder into a case as with a full power hand load (which is hard on your rifle) that builds more and more pressure. We are opening up the case to allow for more capacity, and thus the pressure will stay within reasonable parameters.
After thinking about my idea I decided to see what other people thought about the cartridge that I designed? Everyone liked the idea, but thinking that maybe those that knew me ... only wanted to be nice?? I decided to send the drawing to a couple of people on a few forums to see what they thought about my idea. Again it was well received, and people thought that it would be a good idea if someone wanted to have a little more from their hunting rifle.