August 31st, 2015

Can’t Find Varget or Reloder 15? Then Try IMR 4320

IMR 4320 Varget Powder Hodgdon reloading 6mm Dasher

IMR 4320 Varget Powder Hodgdon reloadingWhile 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 [2009] 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
IMR 4320 3890 0.5920
Alliant Reloder 15 3990 0.5200
Hodgdon (ADI) Varget 4050 0.6150

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

Permalink Bullets, Brass, Ammo, Reloading 8 Comments »
December 4th, 2012

“Forgotten” IMR 4320 Powder Yields Great Results

IMR 4320 powderIn his Riflemans Journal Blog, German Salazar has authored an excellent article on IMR 4320 — The Forgotten Powder. German tested IMR 4320 and found that it produced outstanding results both in the .308 Winchester and the 30-06. This means that shooters have another very effective propellant option for their .308 and 30-06 match rifles. With H4895 and Varget being hard to obtain lately, you may want to give IMR 4320 a try.

German writes: “IMR 4320 falls right between 4895 and 4064 on the burn rate scale for most cartridges — in other words, right where Varget falls. Yet, despite having a very useful burn rate, 4320 has languished for decades while newer powders of similar burn rate have gained in popularity. I was interested in seeing what current production IMR 4320 would do in the .308 with the 155gr Palma bullets. My interest was sparked by the obvious fact that Varget and H4895 have been very hard to get lately while IMR 4320 sits on the shelves.”

German loaded up some .308 Win loads with IMR 4320 and moly-coated Sierra 155gr Palma bullets. German’s “practical max” load delivered 2990 fps in his long-barreled Palma rifle. This is certainly competitive speed-wise.

German observed that: “IMR 4320 has very small granules and throws very consistently from the powder measure — it is very much like Reloder 15 in granule size — so for those who prefer to throw charges it’s a good choice.”

Satisfied with the chron results, German loaded more rounds with the two most promising charge weights and used them in a 500-yard prone match at Ben Avery (ambient temps were 60s-80s F). Here is his report:

“As in the chrono tests, all IMR 4320 loads were with moly-coated Sierra 155 Palma bullets, Winchester brass and PMC primers. Powder charges should be reduced at least 1.0 grain for bare bullets. The load with 45.0 grains of IMR 4320 gave me a 199-12X with the single 9 being a high shot just off the 10 ring line at 12:00. Overall, I would rate that load as good, very useable for the intended purpose of 500 or 600 yard shooting (it’s 2844 fps) but no better than my H4895 load for that purpose.

Next I fired the heavier 47.0 grains ‘practical max’ load and that was an eye opener. The score was 200-15X in conditions that were windier than those in which the first load was fired. Elevation was noticeably tighter and shots were exactly on call. This load gives 2990 fps, so it has real potential as a Palma load. While no 500-yard test can ensure results at 1000, given the MV and reasonably low SD of this load as well as the good performance at 500, I won’t hesitate to shoot it at 1000 at the first opportunity. Warning: this was a STRONG LOAD and may not be safe in your gun.

Overall, I’m very satisfied with what I’ve seen in these past few days from IMR 4320 and plan to shoot it in some of our upcoming Palma and 1000-yard matches with the 155s. It appears to be a very useful alternative to some of the harder to get powders.”

CLICK HERE to Read Complete IMR 4320 Story (includes chron data and match test results).

Permalink Competition, Reloading 12 Comments »