The .25-caliber ACP (Automatic Colt Pistol) is a diminutive centerfire cartridge designed by John Browning. The cartridge originally was used in small, semi-automatic “pocket” pistols such as the FN model 1905. It was introduced in the United States in 1908 with the Colt .25 “Vest Pocket” pistol. Its low muzzle energy and poor terminal ballistics make it unsuitable for either hunting or target shooting, and it is only marginally effective as a self-defense cartridge. Because of its small size and low case volume, safely reloading the .25 ACP cartridge requires both an accurate powder scale and extreme attention to detail.
1. Prepare the common components for your reloading session. While the specific bullet type and propellant you use will depend upon the specifications for your chosen load (called a “recipe” by handloaders), the process will always require clean, lubricated brass casings and small pistol primers. Also ensure that your powder scale is properly calibrated because the small .25 ACP cartridge is very sensitive to variations in propellant weight.
2. Resize and remove the spent primers from your brass casings by running them through the sizing/decapping die on your reloading press. Press a new primer into each cartridge using the hand priming tool. After priming, place all cartridges in a cartridge tray with the case mouth facing upward.
3. Charge each casing with propellant according to your selected handload’s recipe. Self-defense load recipes use a 50-grain FMJ (full metal jacket) bullet. Match this bullet weight with a load of 1.2 or 1.3 grains of Bullseye powder, or a load of 1.4 to 1.6 grains of Accurate Arms Number 2. Be careful not to over-charge any of the casings.
4. Run each cartridge through the bullet seating die on your press to seat and crimp the 50-grain FMJ bullet. Use your precision calipers to measure a sampling of the finished cartridges to ensure they fall within the mechanical tolerance for the .25 ACP’s overall cartridge length. The acceptable range for cartridge length is from 0.908 inch to 0.910 inch.