Guide to IMR’s Enduron Powders — What You Need to Know

IMR® Legendary Powders now offers four (4) Enduron powders: IMR 4166, IMR 4451, IMR 4955, and IMR 7977. Shooters looking for readily-available alternatives to hard-to-find extruded powders should definitely check out the Enduron line-up. Precision shooters will find an Enduron option well-suited to most of the popular precision cartridge types. For example, IMR 4166 is a good replacement for Hodgdon Varget (commonly used in the .223 Rem, 6mmBR and .308 Win), while IMR 4955 is a fine substitute for H4831 (favored by F-Open shooters for the .284 Win and 7mm WSM cartridges).

Modern Powder Technology for Enhanced Performance

The technology in IMR’s Enduron line of powders provides four very important qualities that enhance both in-gun and downrange performance.

Copper fouling reduction – these powders contain an additive that drastically reduces copper fouling in the gun barrel. Copper fouling should be minimal, allowing shooters to spend more time shooting and less time cleaning a rifle to retain accuracy.

Temperature change stability – the Enduron line is insensitive to temperature changes. Whether a rifle is sighted in during the heat of summer, hunted in a November snowstorm or hunting multiple locations with drastic temperature swings, point of impact with ammunition loaded with Enduron technology will be very consistent.

Optimal load density - Enduron powders provide optimal load density, assisting in maintaining low standard deviations in velocity and pressure, a key feature for top accuracy.

Environmentally friendly - Enduron technology is environmentally friendly, crafted using raw materials that are not harmful to the environment.

The Enduron Line-Up of Four Powders

IMR now offers four Enduron powders that cover a broad range of burn rates. They are suitable for a wide variety of cartridges, from small varmint cartridges all the way up to the .338 Lapua Magnum.

IMR 4166 possesses the fastest burn rate in the Enduron lineup. It is the perfect burn speed for cartridges such as .308 Win, 7.62mm NATO, 22-250 Rem and 257 Roberts. A versatile, match-grade propellant, IMR 4166 is comparable to Hodgdon® Varget.

IMR 4451 is a mid-range burn speed powder, ideally suited for cartridges such as .270 Winchester, .30-06 and 300 Winchester Short Magnum. This powder is comparable to Hodgdon H4350.

IMR 4955 is a medium burn speed powder, falling in between IMR 4451 and IMR 7977 in burn speed. It provides top performance in big game cartridges such as 25-06, 280 Remington and 300 Winchester Magnum. This powder is comparable to Hodgdon H4831.

IMR 7977 has the slowest burn rate among the Enduron Technology powders. Its loading density is perfect for magnum cartridges and contributes to superb uniformity, yielding outstanding performance in 300 Winchester Magnum, 7MM Remington Magnum and .338 Lapua Magnum. IMR 7977 is comparable to Hodgdon H1000.

The Enduron Technology powders are available in one-pound (1 lb) and eight-pound (8-lb) containers from quality reloading retailers. Learn more about Enduron powders at www.enduronimr.com. For info on other IMR powders, visit www.imrpowder.com.