Wildcat Cartridge Chart

What makes it a wildcat

A wildcat is a cartridge that isn't standardized by SAAMI or C.I.P. There's usually no factory ammo, so you form brass from the parent case listed under each name, handload it, and have a gunsmith chamber the rifle with a matching reamer. Dimensions and load data can vary from one gunsmith or source to the next.

Ackley Improved

P.O. Ackley's method blows out a parent case with less body taper and a sharp 40° shoulder. You get more powder space, roughly 100–150 fps more, and brass that stretches less. Most Ackley chambers can safely fire the parent's factory ammo, which fire-forms the new brass as you shoot.

How the numbers are figured

• MPBR uses a 4" zone for varmint rounds and a 6" zone for the rest, a scope 1.5" over the bore, sea-level air and a G1 drag model.
• Velocities and BCs are typical published handload figures as I know them, not looked up. Your load, barrel and brass will differ.
• Size outlines are simplified sketches from typical chamber dimensions, on a 1" grid.
• Always start with published load data and work up carefully; wildcats have no factory pressure standard.