So, working with the 12 gauge fh has given me a huge amount of knowledge on cartridge design. I have noticed some pitfalls with the 12 ga fh since I started loading it.
1- sectional density- The giant slug has a lot of energy, but poor penetration due to a large frontal area.
2- Brass availability- the brass is really expensive $10 a pop and takes months to get. If you use 50bmg brass you have to use a lathe to add a thread on rim.
3- Ease of loading- this brass is fantastically made, but it's lathe turned and VERY thick. That means FL sizing is impossible. Also, getting a die has proven to be difficult
So, with all that said, I got to thinking. What I propose sounds kinda crazy, but that's why I like it.
So, with 50 bmg as the parent case, I want to neck up to .615" (20 gauge) this offers a much better SD that the .729" pill. The first loadings will use standard 50 bmg load data. For the action, I want to use a single shot 50 bmg action ($850) with a custom barrel. This way, you can use 50 bmg brass without having to add a rim. Also
FL resizing is now possible with a 50 bmg press. I can also get a repeater action instead of the single shot down the line. Velocities will be a bit higher than 12 ga fh too as I can load it quite a bit hotter due to the strength of the action. Another great benefit is I would no longer need to mix powder as the 50 bmg primer is sufficient for ignition!
A few problems I will have are
1- I have to get the cartridge approved by the ATF as it's over .50"
2- getting a die that will size the brass
What do you guys think? I've never made a wildcat cartridge before, but I feel I have the knowledge to do so now. I believe this would make an amazing safari/stopping cartridge. I'm pretty confident I can get muzzle energy to the 10k+ ft-lb realm as they were doing that with 12 ga fh with the rimmed 50 bmg brass.
Also, a lot of you guys are very smart, and helped me out tremendously with my 12 ga fh, so help and suggestions from y'all would be fantastic.