While Varget and Reloder 15 remain in short supply, you can often find IMR 4320 powder back in the shelves of local gun stores. IMR describes IMR 4320 as follows: “Short granulation, easy metering, and perfect for the 223 Remington, 22-250 Remington, 250 Savage and other medium burn rate cartridges.” This older-generation powder is more temp sensitive than the Hodgdon Extreme propellants, but in the right application, it looks to be a viable alternative for folks who can’t source Varget, Reloder 15, and even H4895.
IMR 4320 Shoots Well in the .308 Winchester
A while back, German Salazar wrote an excellent Riflemans Journal article, IMR 4320 — the Forgotten Powder. German developed IMR 4320 loads for his .308 Win Palma rifle and competed with IMR 4320-powered ammo at long range matches. German concluded that: “[IMR 4320] appears to be a very useful alternative to some of the harder-to-get powders. The load is working extremely well at 1000 yards. In the  Arizona Palma State Championship, several high placing competitors were using the 4320 load. We got sub X-Ring elevation at 1000 yards from several rifles, and that’s all I’m looking for in a Palma load.”
IMR 4320 Works for Dasher Shooter
Forum member FalconPilot shoots a 6mm Dasher with Berger 105gr Hybrids. Looking for an alternative to Varget, he decided to give IMR 4320 a try. The results were good. FalconPilot reports: “I’ve been looking for other options (besides Reloder 15, which I love, but it’s really dirty). While at a gun shop in Ohio, I ran across 8 pounds of IMR 4320. I had never even heard of it, much less tried it. Getting ready for upcoming mid-range shoots, I loaded five rounds with IMR 4320 to the exact same specs as my winning Varget loads for the 6mm Dasher. This recipe was 32.7 grains of powder, Wolf SMR primer, Berger Hybrid 105 jumped fifty thousandths.” Falcon pilot tested his IMR 4320 load at 600 yards:
As you can see from the photo at the top of this article, FalconPilot had good results — a 1.5″ group at 600 yards. He reports: “This group was shoot during the middle of the day, mirage bad, scope set to 25X. It looks like IMR 4320 is a [very close] replacement for Varget… with a tad bit slower burn rate.” FalconPilot tell us the accuracy with IMR 4320 rivals the best he has gotten with Varget: “This gun has always shot under 2 inches [for 5 shots] at 600 yards, and most of time shoots 1.5 to 1.7 inches.”
For comparison purposes, here are Heat of Explosion and Burn Rate values from QuickLOAD for IMR 4320, and for the popular Reloder 15 and Varget powders. You can see that these powders have similar characteristics “by the numbers”:
|Manufacturer||Powder Brand||Heat of Explosion||Burning Rate Factor|
WARNING — When changing from one powder to another, always start with manufacturer’s stated load data. Start low and work up incrementally. Never assume that loads will be equivalent from one powder to another, even powders with similar burn rates.
What Other Forum Members Say:
I was using IMR 4320 in the mid 70s in my .222 Rem. Darned great powder and I never had a load that was not accurate from the .222 to .30-06 with that powder. — 5Spd
A fine powder overshadowed by the nouveau wave of “gotta have the newest — make me a better shot” powders. Try 4320 in a 22-250 — what a well-kept secret! IMR 4320 meters very well and is a flexible alternative to many of the hard-to-find powders so much in demand. — AreaOne
IMR 4320 was my “go to” powder in my .223 for many many years. This powder and Winchester 55gr soft point bulk bullets (the cheapest bullet I could buy at the time) accounted for thousands of prairie dogs, coyotes, and anything else that needed shooting. I still use IMR 4320 in some .223 loads and am very happy with it still. — pdog2062
I’ve been using it in a .308 Win for several years. I think it is very sensitive to temperature and always waited till the last minute to load my ammo with a close eye on the weekend forecast at the range. IMR 4320 Works pretty good for 155gr Palma and 168gr Hybrid [bullets] in my .308. — JayC