How to Fire-form a Case

••• shell image by Roman Sigaev from Fotolia.com

Wild Cat loads are non-standard firearms cartridges not available through commercial manufactures. The Wild Cat cartridge must be re-sized from the commercially available brass with a re-loading die that reshapes the brass case. The re-sized brass must then be fired in the gun, using a reduced powder load so that the internal pressure caused by the power burning forces the brass cartridge to expand and conform to the exact chamber dimensions. Once the brass case has been fire-formed, it can be loaded to its maximum pressure.

Set up your reloading press as normal, depending on the make and model of press. Re-size the standard brass case with the Wild Cat resizing die in the same manner as you would a standard re-sizing die.

Consult your reloading manual or data sheet for the Wild Cat cartridge and select the lightest powder load recommended for the bullet weight you are using. Charge the case with the recommended powder load and seat the bullet as you normally would, depending on the make and model of loading press.

Load the cartridge in your gun at a safe firing location then fire the cartridge. This initial firing will cause the relatively soft brass case to expand and conform to the gun's chamber dimensions.

Remove the form-fired case from the gun chamber and inspect it for any damage, such as a split casing, detached head, excessive pressure or a dented shoulder. Damage may indicate excessive pressure and will require you to re-evaluate the powder load and bullet weight. Developing the proper powder load and bullet weight may require some experimentation, and care must be taken so that dangerous pressures do not develop.


  • Reloading Wild Cat cartridges (fire-forming) is experimental and inherently dangerous. It should only be attempted by someone with several years of reloading experience.


  • Use new, unfired brass cases when re-sizing commercial-sized cases to Wild Cat case dimensions.


  • "The Handbook of Metallic Cartridge Reloading"; Edward Matunas; 1981
  • "Metallic Cartridge Reloading"; Mic McPherson; 1996
  • "Rifle Cartridge Reloading, Step by Step. Second Edition"; Christopher Ohland; 2009

About the Author

Living in Tucson, Gerry Arlen Good has been writing for 34 years in a wide variety of environments including government, military and business. Good received a B.S. in psychology from Fitchburg State College and is a graduate of the U.S. Army Command & General Staff College.

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