Developing a wildcat cartridge

[GSPBirdDog]

I have been a machinist for the past 20+ years and have occasionally modified dies for people making wildcat rounds. One of the guys i did work for was Ferris Pindell. He was one of the developers of the 6mm PPC cartridge. Such a wonderful man and i wish i could have picked his brain before he passed away.

My question is, how do people develop a wildcat cartridge? How do they know what powder to use and what amount? How do they test chamber pressure ect.. I have heard of guys filling the case up with water and measuring the volume of the case.

Any insight would be great!

 

[Clay Pigeon]

I use Quickload software.. The more data you give it the more data it gives you back right at your loading bench. Money well spent..

 

[NKBJ]

Mine was a 375x45-70 with a long neck to contain and protect from contamination a lot of lube grooves while making best use of soft enough alloy and slow enough powders for a flat shooting and accurate cracker jack 200 yard deer hunting rifle.
The development process was one of setting the intended performance goals and then a couple of years of experimentation with techniques, case geometries and propellants. Along the way "what works" became understood. The bullet diameter and weights were chosen. The case geometry was designed to fit a chosen action and be conducive to producing the hunting rifle handling characteristics wanted, to get the case volume, the funnel effect constriction, the head spacing, the support for alignment, for forming difficulties, brass availability. The process was similar to WW1 aircraft design in that if it seems right it is right and successful designers had the appropriate programming between their ears. Designers with inappropriate programming made goofy planes that didn't work. I knew I had a winner so I went with it.

I did consider a lot of different options based upon using some already established cartridge designs. An example would be that you take brass of a given case head and use it in the shortened sizing die of some other cartridge. Doing it that way there are several combinations that could have worked with various bullet diameters. But I wanted the best I could come up with and saw no reason to compromise. Once drawn up with the needed design data I turned the job with the firearm to be used over to a gunsmith of previously proven capabilities and trustworthiness.