Ammunition Safety Facts: Wildcat Cartridges

Handloading your own ammunition has plenty of benefits, but there are some things to know to stay safe!

by
posted on December 19, 2023
35 Whelen Ackley Improved

In addition to factory-produced cartridges for which the Sporting Arms and Ammunition Manufacturers' Institute (SAAMI) has developed dimensional and pressure standards, there are also non-standard "wildcat" cartridges developed by ballistic experimenters. Often a wildcat round is produced simply by necking up or necking down the cartridge case of a factory standard cartridge; sometimes other case modifications, such as reducing case body taper or sharpening the shoulder angle, are also performed. By definition, wildcat ammunition must be produced by reloading

In terms of safety, wildcat ammunition raises two issues. First, firearm chambers for wildcat cartridges may sometimes loosely accept other standard cartridges as well, creating a situation in which there is excessive headspace or case body clearance. If the standard cartridge is fixed in a wildcat chamber, potentially dangerous case head separations or case body splits could result. (The exception to this is the "Improved" wildcat chamber, which is designed to allow the safe firing of factory ammunition.) 

The second safety issue relating to wildcat cartridges relates to standardization. SAAMI publishes recommended cartridge and chamber dimensions, as well as maximum pressures, for factory ammunition produced in the United States; the Commission Internationale Permanente des Armes a Feu Portative (CIP) does the same for European-made ammunition. These standards provide a benchmark for ammunition manufacturers, gun makers, gunsmiths and others in the firearm industry, and ensure that all ammunition of a given caliber is safe to fire in virtually any firearm chambered for it. 

No such standards exist for wildcat cartridges. Minute differences in the shoulder angle, neck length and body taper of a case, or the neck diameter or throat length of the chamber, as well as the lack of pressure standards and pressure-tested load data, all make the assembly of wildcat loads challenging, even for highly experienced reloaders.

Compounding the problem is the fact that many wildcat rounds were created for target competition, and were thus designed to be used in guns with competition-type chambers having tight necks, custom throats and/or minimum SAAMI dimensions. 

Any shooter who has acquired a gun (particularly a rifle) chambered in a wildcat caliber should first have a competent gunsmith make a cast of the chamber and throat. From this, proper cartridge dimensions can be obtained.

Note that NRA recommends reloading only using pressure-tested loading data published by reputable sources, such as the manufacturers of powder, bullets and other cartridge components.

Latest

2025 Mossy Oak Wild Turkey Stamp
2025 Mossy Oak Wild Turkey Stamp

Mossy Oak Announces 2025 Wild Turkey Conservation Stamp

All proceeds from stamp sales go directly to wild turkey conservation projects around the country.

MidwayUSA Named Official Sponsor of the 2025 NRA Annual Meetings & Exhibits

GLOCK, Inc. is the Presenting Sponsor of the Freedom Experience on Saturday, April 26th.

3 Welcome Surprises of Concealed Carry

What the author thought were invisible hurdles to CCW turned out to be welcome surprises ... you may find the same!

Video How-To: Choose the Best Ammunition for Your Gun

It's a bit more complicated than just checking the markings on your gun's barrel. We explain!

Throwback Thursday: Counting Coup (How "Brave" Are You?)

What did American Plains tribes believe brought more pride and honor: ending an enemy, or just humiliating him?

NRA Lauds VA Governor Youngkin for Vetoing Two Dozen Anti-2A Bills

The bills vetoed by Governor Youngkin came from the long wish list of radical gun control activists.

Interests



Get the best of NRA Family delivered to your inbox.