How to Reload the .45 Colt With IMR 4227 Powder

How to Reload the .45 Colt With IMR 4227 Powder

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Adopted by the U.S. Army as its service handgun cartridge in 1873, the .45 Colt quickly became a favorite among civilian shooters. The cartridge, also known as the .45 Long Colt, served the U.S. military for 17 years, but persists as a popular "cowboy shooting" and handgun hunting cartridge to this day. IMR 4227 is a medium-burn-rate, Magnum smokeless propellant produced by the Hodgdon Powder Company. IMR 4227 is recommended for use in defensive and hunting hand-load recipes for the .45 Colt. The propellant generates higher chamber pressures and heat that may produce extra fouling when used in target loads based on lead or lead-alloy bullets.

Items you will need

  • Reloading press

  • .45 Colt brass cartridge cases

  • Magnum pistol primers

  • Jacketed bullets

Make sure your hand-loading recipe matches the correct bullet type and weight for use with IMR 4227. Develop your initial batch of reloads based on the smallest propellant charge recommended for the cartridge. The most common reloading recipes recommend the use of copper-jacketed bullets with IMR 4227. Minimum propellant specifications range from 17.0 grains with a 200-grain jacketed bullet to 15.8 grains with a 260-grain jacketed bullet.

Run your cartridges through the resizing and decapping die on your reloading press. The .45 Colt cartridge features an ample case rim, so you should have no problems with cartridges slipping in the shell holder.

Insert new primers into your .45 Colt cartridges. If your reloading press features a priming attachment, you can make use of it to speed the hand-loading process. Otherwise, use a hand priming tool to press new primers into place. .45 Colt hand-load recipes that make use of IMR 4227 are considered Magnum loads and require the use of Magnum pistol primers for proper ignition.

Charge the reprimed cartridges with your recipe's recommended load of IMR 4227. If you're using an automatic powder trickler mounted on your reloading press, periodically check the load delivered to your cartridges by using a powder scale.

Complete the assembly of your hand loads by topping each cartridge with a copper-jacketed bullet and running it into the bullet seating die on your press. Make sure that the seating die is properly adjusted to press a slight crimp into the case mouth where it meets the cannelure of the jacketed bullet.


  • The Colt Single-Action Army revolver, chambered for the .45 Colt, has been in production longer than any other type of American-made handgun. IMR 4227 generates chamber pressures considered excessive for safe use in vintage firearms. Only use loads based on IMR 4227 in firearms manufactured since the end of World War II.
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