9.3 wildcat

[Rimshot]

I spent a few days playing around with QuickDesign and QuickLoad.
Let me know if this one has been done before.

I want a powerful rimmed cartridge because I like single shots. This isn't strictly Africa focused, but suited to open country on large game.

Goals:
Smooth function in break open and single shots (rimmed, adequate body taper, etc)
Tolerable recoil in <10 lb gun
Meet/exceed 9.3x64 Brenneke performance at 9.3x74R pressures (this means more powder obviously)
Dimensions allowing for easy rechambering of 9.3x74R barrel
Under 3" case length to fit in Hornady hydraulic form die
Easy to acquire parent case

Most likely I will do this in a T/C Encore, before I rechamber something like a K95 or a falling block.

Why 9.3? I think it strikes a compromise of good frontal diameter, bullet weight, construction, SD, and reasonable BC in a number of bullets - without needing a 12 pound gun or muzzle brake to tolerate Sir Isaac Newton at these higher velocities. Of the Swift A-frame Heavy Rifle bullets, the 9.3 286 has the highest BC of any other caliber. For long range energy retention, the Nosler 9.3 250 Accubond and Hammer 242 tipped mono both have a G1 BC of around .5

For parent case I used the 450/400 3". I lengthened the body and made a 30 degree shoulder, leaving a decent amount of body taper (similar to the 500/416 NE). Case capacity is around 118 grains of water. While keeping pressure under 50k psi and depending on powder choice, a 286 A-frame should get 2650-2700 fps out of a 24" barrel, and a 250 gr bullet around 2850. Of course a longer barrel would give you more.

I realize modern single shots can handle much higher pressures (60k+), however, the 450/400 was limited to ~40k, and I am not aware of any other large capacity rimmed parent cases that would be suitable. I will need to discuss with a ballistician about how new 450/400 cases are made, since I know it is the basis for the 404 jeffery, which in turn fathered most of the modern rimless magnums. Maybe someone can section a new 450/400 case and compare the web/wall thickness...for science?

I welcome all your suggestions and criticism. Obviously there is no real "need" for this, mostly "want". You can disregard some of the chamber dimensions, as I haven't completed that yet. All of this is an evolving work in progress.

 

[grand veneur]

As a fan of 9,3mm cartridge, especially the 9,3x64 Brenneke, I can only agree with such a cartridge, but for practical reasons, I would have choice the caliber 375. Such a rimmed cartridge would certainly also interest many African hunters and with the 9,3mm caliber we are operating in a gray zone in some countries when it comes to the minimum required for DG hunting. Ballistically 9,3mm and .375 caliber bullets are almost identical. Nevertheless, this cartridge could fill a gap in the class of the 9,3mm rimmed high-performance cartridges. We have some of rimless ones in this caliber class, but none powerful rimmed.

 

[coreydb]

I agree with Grand Veneur. I have a 9,3 as well, but too many PHs (with whom I hunted with) won't allow their clients to hunt DG with 9,3s, even in countries that allow it.

 

[Rimshot]

I completely agree with you guys that 375 broadens the horizon to the DG use case, and that 0.009" or 0.2mm delta of bore diameter is functionally meaningless. It would be trivial to neck up the current design to a .375 Flanged Ultra Mag (375 FUM? FLUM?)

I see this as more specialized though, with no regard to it's legality or PH happiness on DG. For DG i'd prefer something in .4xx". If I were more focused on DG, I would simply chose the appealing 500/.416 NE.

In some ways a .338 diameter would provide a lot of advantages with the large array of efficient bullet designs, but then you're giving up frontal area and bore capacity.

Anyway, there are a bunch of other cartridges out there that already have more all around versatility than this one. I'm under no illusion that anyone else would want or need one of these. I found myself wanting a longer range medium bore rimmed cartridge, and there seems to be nothing available.

Another factor is that some rifles I have an eye on (like the Blaser K95) don't offer a 375 bore, and no custom barrels are available. It seems theoretically possible to rechamber a 9.3x74R though, especially since they offer 10.3x60R as well, so we know the parent case of my new cartridge will fit!

 

[odonata]

Goals:
Smooth function in break open and single shots (rimmed, adequate body taper, etc)
Tolerable recoil in <10 lb gun
Meet/exceed 9.3x64 Brenneke performance at 9.3x74R pressures (this means more powder obviously)
Dimensions allowing for easy rechambering of 9.3x74R barrel
Under 3" case length to fit in Hornady hydraulic form die
Easy to acquire parent case

This is an interesting challenge simply because I enjoy exploring the possibilities.

Option #1: Choose the 9.3x74r. I suggest this simply because I like my Ruger No. 1S so much. I currently have five different cartridges from 184gr to 286gr to choose from. I can cover a lot of situations with this cartridge alone without resorting to a more challenging wildcat.

Option #2: A 9.3 bullet is a .366 caliber. Just go up a bit & embrace the 375 H&H Flanged. Lots of bullets to choose from. Commercial ammo is available.

Option #3: You just feel like doing a wildcat because it's fun to be creative. An option that intrigues me is the 416 Strauss. This may be of no interest to anyone else but as someone who has a nostalgic fondness for the 303 British & who lives in a straight-wall state, it has some characteristics that makes me think it might be a wildcat I would want to look at. Basically it's a 303 British case that has been upsized to accept a 416 bullet. The end result is a straight-walled rimmed cartridge that delivers 375 H&H power. You're looking at 300gr @ 2500 fps producing 4164 ft/lbs so it can deliver a solid hit that's only a little short of the 9.3x64 Brenneke. The more common 35-303 British wildcat with a .358 bullet would be another option to explore.

Just a few suggestions to either get excited about or throw rocks at.

 

[Mountaineer]

Very interesting. Good luck.

 

[fsrmg1]

Almost sounds like you have dreamed up is the .369 Purdey Nitro Express, just a bit longer case. Why not go with the original classic round and take advantage of modern powders and projectiles to enhance the performance.

 

[grand veneur]

Almost sounds like you have dreamed up is the .369 Purdey Nitro Express, just a bit longer case. Why not go with the original classic round and take advantage of modern powders and projectiles to enhance the performance.

In practice, you don't need anything new or improved for a long time. With the cartridges that are on the market for 100 years and more, almost everything is covered for hunting worldwide. Sure, there are older cartridges that can be improved with modern powders and bullets, although you can quickly reach limits due to internal ballistic problems and there are often no rifles that can safety fire such improved cartridges. That's why you need such cartridges just as little as you need all the various improved wildcats, but it is always fun to develop something new, even if it is not really needed.