Wildcat Cartridges for Handguns

There are still some gaps to fill!

43Auto / 11mm Auto

A .44-caliber cartridge for common semi auto pistols

At the first glance it is astonishing that there are only few wildcats for handguns. But it is much easier and cheaper to buy and install a barrel in a rifle action -whether new or reworked- than building a pistol barrel and make it function flawlessly. And a new cylinder for a revolver is anything but easy to manufacture.

This leaves room for more or less new designs.

A neglected calibre for semi automatic pistols is .44 (.429 bullet dia.) which is so popular in revolvers.

An early famous attempt to build a 44-caliber self loading pistol and cartridge was the 44 Auto Mag(num Pistol) in the early 70’s. Though it helped to make Dirty Harries day it didn’t really survive. Maybe it was too much gun and cartridge to be attractive outside a special interest group. That could be dramatically changed when you are focused on Colt 1911 size handguns and if the new cartridge has a significant advantage over the venerable ones.

The 43 Auto is intended for 45 ACP semi auto pistols. It is based on a shortened 44 Special, 44 S&W Russian or 44 Magnum case with the rim and extractor groove turned down to 45 ACP dimensions. As the rim is slightly larger than the base it is in fact a semi rimmed design but it headspaces at the case mouth. A new barrel and a new main spring are mandatory and could be enough for switching to this calibre. An unknown factor is feeding this type of case out of a 45 ACP magazine in a particular pistol model.

According to QuickLOAD this cartridge offers the same performance as the 10mm Auto but at considerably lower working pressure:

Barrel Length: 5”/127mm

Bullet Weight: 200grs

Total Inside Volume of Case: 25.5 grs of water

Maximum Working Pressure: 26.100psi / 1800bar

Muzzle Velocity: 1200fps / 365m/s

These QuickLOAD data seem to be plausible because a .429 dia bullet has a lower sectional density than a .400 dia bullet of the same weight. Lower sectional density means better acceleration inside a barrel –and higher drag outside.

The 11mm Auto is identical in performance if powder space volume is equal. Its rim diameter will be a problem for most pistols designed for 45 ACP. The bolt face of the slide must be adapted. Additionally or alternatively the operating angle of the extractor must be increased. Cases for the 11mm Auto can be built without a lath but a special die set including a reamer for removing inside material can not be substituted while the 43 Auto simply uses dies for its parent case and a 45 ACP shell holder.

48 Auto

The ‘475 Wildey Magnum Short’ = 380 Auto on Steroids

A 475 caliber handgun cartridge is still exotic. In 2014 someone in a Colt 1911 forum had the idea of shortening the 475 Wildey Magnum to a case length of 0.9 inch for using it in a 45ACP pistol. The 48 Auto is nearly identical to this proposal. Wildey Magnum cases are currently available from Starline and shortening would be an easy operation. In a 45ACP pistol with a high capacity magazine “only” a new barrel is necessary. Frames built for single row magazines will be a challenge for passionate pistol smiths.

Asking QuickLOAD one gets these predicted values:

Barrel Length: 5”/127mm

Bullet Weight: 240grs

Total Inside Volume of Case: 30.6 grs of water

Maximum Working Pressure: 23.200psi / 1600bar

Muzzle Velocity: 1170fps / 356m/s

Barrel Length: 5”/127mm

Bullet Weight: 280grs

Total Inside Volume of Case: 30.6 grs of water

Maximum Working Pressure: 23.200psi / 1600bar

Muzzle Velocity: 1080fps / 329m/s

Recoil of a 48 Auto pistol of that performance would be more than enough for most shooters.

It is still possible to find information about the 475LeHigh. It follows the same design philosophy as the 48 Auto but is based on the 480 Ruger case.