IMR-4350

PROPELLANT PROFILES

- Randy Bimson

Readers of this column may soon discover I have a passion for classics as well as modern technologies. It will come as little surprise then, that this, the first “Propellant Profiles” column I pen, takes a look at one of the all-time classic centerfire rifle propellants.

Purportedly at the time of its introduction, noted authority Phil Sharpe reported that DuPont developed IMR-4350 to optimize the performance of the only “magnum” cartridge of the time, the .300 Holland & Holland Magnum. True or not, with the introduction of IMR4350, cartridges like the then-wildcat .22 Varminter (.22-250) and .25-06, the .270 Winchester and the .300 H&H Magnum, all of which would have been considered overbore capacity at the time, received a much heralded boost in performance from IMR-4350.

In the first “Propellent Profiles” review of IMR-4350 in 1970, John Wootters described it as a “landmark” powder (Handloader No. 27, September-October). IMR-4350 was a game-changer when it was introduced in 1940 and continues, 80 years later, to define the velocity and accuracy potential of many of the latest cartridge designs. IMR-4350 has become the propellant of choice of handloaders who find it a well-balanced powder for a broad selection of the “fat case, small diameter projectile” cartridges that have become, some more, some less, popular in more recent times. These include cartridges like the .22 CHeetah MKI & MKII, 6.5-284 Norma, 6mm and 6.5 Creedmoor, .270 and .300 Winchester Short Magnum, 7mm and .300 Remington Short Action Ultra Magnum and the .300 Ruger Compact Magnum.