Has anyone ever created a true wildcat cartridge from the ground up, and built/chambered a firearm for it?

What was your motivation for doing so?

Would you consider it to be "worth it" for you, or would you have done things differently if you had to do it again?

Did you get what you were looking to get out of it?

I've always thought it'd be cool to design my own cartridge, probably the easy way (necking down/up an existing case), but I always thought it'd be so cost prohibitive for so little ROI that I hadn't pursued it. Now that I understand a lot more about reloading I've started to consider the idea.

50 or 60 years ago I'd have said go for it. Today, not so much. If you look at a comprehensive current cartridge chart you will see that for virtually every specific bullet diameter, there exists multiple necked up/necked down variations. Yes there have been some "new" cartridges come along in recent years such as the 350 Legend, 450 Bushmaster et al. But most of those cartridges were designed to shoehorn a particular caliber/bullet into a particular action type.

I think your time and energy would be better spent picking out a cartridge that provides the performance you are seeking from your wildcat idea, and putting time and money into building a gun that squeezes maximum performance from that cartridge. All that money you'd spend on reamers and custom barrels could be spent on components instead.

But, if ya just gotta scratch that itch............ Thats why we have several hundred current and obsolete rounds in existence. Get an older copy of Frank Barnes' "Cartridges of the World" and see if you can find an unfilled niche in there somewhere.

ETA: The one factor that has thrown a wrench into things are all of the newer powders that potentially allow you to squeeze more performance from a given bullet. But depending on whether you are looking for more velocity or more throw weight, you can accomplish that by going up or down one common bullet diameter just as easily. And before we hear from the various Nosler, ARC, Creedmoor fans, those cartridges performance can be had with other existing cartridges, with the possible exception of some of the "ultra" velocities. But for the costs associated with them, does 200-300 more fps really equate to enough of a difference to matter. For example, how many hogs or deer have been killed with a 30-30 over the last 100 years, versus how many have been killed with a 300 BLK. Not much difference between the 2 cartridges BALLISTICALLY speaking.

jmtcw

I wouldn't say ground up but I was definitely in uncharted waters. I got 2000fps from 230gr bullets from a vaguely .45acp size cartridge using Mauser rifle with an 18" barrel without pushing pressures to brass damaging levels. It's a riot of a gun to shoot and hits hogs like the fist of an angry deity.

I didn't do it for any other reason but to see how fast I could get the bullets going before opening up primer pockets.

I thought about expanding the necks on my .300 win. magnum, shortening the case, changing the shoulder to 40 degrees, then I realized P. O. Ackley had basically already done it for his .35 Ackley improved magnum.

Yes... friend and I were shooting Metallic Silhouette in the late 70's, shooting cast bullets... we wanted something with more case capacity than the 7TCU, and built a necked down 7mm on a 30/30 case we called the 7x51 RMS... 7x51 Rimmed Mickewicz Snyder (I'm the S)... blew the case out to around an 8degree taper and 45 degree shoulder... Mick shot a couple of 40x40 out of a 14" TC Contender that Clymer provided the reamer for as well as for Redding to make the loading dies... I chamber reamed 3 barrels... don't know where the reamer went after that... a short time after we reported it to the "Silhouette" news paper, the new "wonder cartridge"was released by the then president of IHMSA... the 7 rimmed International...

it's a dangerous addictive hole to go down! lol....Guilty!

24 Mamba AR (Wildcat of a wildcat I developed) Was my poor mans answer to the 6.5g but with "free" brass. Doing 2350 ft/sec(primer flattening at 2380 but still no major ejector impression) with a 108 eld-m from a 14" barrel


22 Adder (again wildcat of a wildcat) Poor mans 5.7 but from a 9mm glock platform also from "free" 5.56 brass. 2200 ft/sec with a 34gr bullet from a glock 34


Then my First, 22 Mamba My stab at a PDW cartridge similar to the Colt MARS cartridge but with some modern improvements. 2550 ft/sec with a 40gr from a 5" barrel, 2225 with a 53gr bullet same length. Also does 3300+ from a 20.5" barrel with 40's and almost 3k with the 53gr.



Then there's ones I have yet to finish.
My answer to the 9x39 using 6.8 SPC family of cases (22 nosler pictured) the 35 Mamba with a 325gr cast bullet I designed/cut a mold for.


Seriously considering a 3rd variation of the 24 Mamba but with the 22 mamba's case length


Then the OG 24 Mamba I have yet to chamber a barrel in yet(Have the blank) It was designed as a inexpensive 1000+yd cartridge for banging steel for fun. Full length 5.56 case "improved" 30 degree shoulder and throated for 105+class bullets keeping them out of the powder column. Should do 2600+ with 105's. From a bolt gun obviously due to the length. Pictured between 5.56 and 243 win. not a fire formed case yet.


Then I also have a 17 Mamba reamer and blank laying around. It's last on the list as I don't have the patients for the brass prep yet!

My one attempt,

Designed and built a 357 HAR (Herret Automatic Rimless).  Used 30 Remington brass cut to length and run through a standard 357 Herret die.  PTG cut the reamer and made GO/NO-GO gauges for me.

It shot surprizingly well but I never managed to get quite the velocity I was after due to lack of case space with so much bullet pushed into the case.  All & all I was very pleased with it, unfortunately it was stolen during a break in.

MLG

Wildcatting...  A great way to prevent unauthorized use.

Every time I even brainstorm about a cool round I find out that it’s been done or at least close enough not to matter. I’m way too vanilla for that nonsense. I absolutely appreciate those that have and continue to do so.

Yep, pretty much totally useless to anyone that can't form their own brass specifically for it.

I've done a few.

500 SOCOM, 475 SOCOM, 458 SOCOM, 44 SOCOM, 10mm SOCOM, 375 SOCOM, 358 SOCOM, 338 SOCOM, 9mm Super, 375 Auto Mag, and 6mm Weatherby RPM.  Still waiting on the reamer for the last one.

The 458 SOCOM is arguably the most popular non-SAAMI wildcat of all time.  Every wildcat I can think of that was hugely popular, ended up SAAMI certified, except the 458 SOCOM.  

Tony Rumore
Tromix

Edited to add: I forgot all about doing a 280 Ackley Long on a Sako AIII action.  The 280 Ackely Imp is 30'06 length, but I stretched the case out to .375 H&H length.
I don't ever recall seeing a standard 30'06 size case stretched out to .375 H&H length in any Wildcat....but maybe it's been done, I don't know.  Anyway, here is a pic of the Ackley Long on the Left and standard 280 Ackley on the right.
Making those Ackly Long cases was a nightmare.  I scrapped a lot of 9.3x74R brass.

When I first posted about it, I got completely crapped on.....but it never made sense to me to have something like a Remington 700 chambered in 30'06, 270, 25-06 etc, when the damn action is long enough to house a .375 H&H length case.
If you're going with a long action, you might as well feed a full length case through it....or better yet, Remington should make a correctly sized 30'06 length action for those cartridges.  You know, like Howa.

What ever happened to the .585 nyati short you were thinking of doing?

It's still in work.  We are about to start cutting metal for our hybrid AR-15 with AR-10 size locking lugs.  The prototype AR-15/10 uppers will probably start off in the WSSM calibers to make sure the design actually works, then we'll upsize the cartridge a bit.
It takes 12-24 months, and costs a pile of money, to create and launch a new caliber from scratch.  We're not going to do that until we are sure our shit will actually work.

I still think I can make the full size 585 Nyati run in an Alex Pro MLR, but that will just be a one-off for personal use.  I have the brass, dies, barrel blank and donor rifle ready to go, but I don't yet have the chamber reamer.  It will be a registered DD.

Tony

Got any 500 SOCOM info? I wish there was an archive of all the stuff you've played with. Is there any advantage to getting 458 SOCOM SAAMI certified at this point?

I have one of your 458 SOCOM uppers and it's been amazing. I've used everything from the 140gr interceptors to 500gr subs.

Been taking a hard look at the 375 since I have an H&H I'll never sell and I reload for it.

Lancers A5s have been 100% for the 458. Any changes that need to be made going to 375? I'm thinking it's tough to get subs to cycle in an AR and instead to go longer on the barrel to optimize supers.

On the 500 SOCOM, I only made one upper, and it was put together to exclusively shoot a 640gr Cast, gas checked bullet.  I had the mould made when I was into the 500 S&W....but that novelty revolver faded quickly from my interest.
With 28.5gr of AA5744 the 500 SOCOM AR-15 tossed the 640gr bullet out of a 16" barrel at 1261fps.  I have no other load data on it.

On the 375 SOCOM, we have a fresh batch of barrel blanks coming in from X-Caliber shortly and plan on dropping our current 18" barrel offering and replacing it with a 16" and 20" version since we've had a lot of guys ask for 375 SOCOM barrels longer than 18".
It will take us 2-3 weeks to get the blanks all machined and finished out.  The 375 will run in the same mags used for the 458 SOCOM.

Tony

That's dementedly awesome! lol

and you have my attention with the WSSM pattern upper. How will this differ from the Olympic Arms WSSM uppers? (not knocking, honestly curious)

I'm not sure exactly how it will be different, but it's pretty clear that the WSSM line is pretty much still-born, so we're not going to continue down that same dead-end path, other than testing our hardware design(s) with the larger diameter WSSM case heads prior to moving forward with a cartridge that someone might actually buy.

Tony

Cool! I have a 7mm RI contender barrel.