“Forgotten” IMR 4320 Powder Yields Great Results
In 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).
just wanting to know if this is a temp-sensitive powder.
Patrick, no more so than any normal, single-base, extruded powder. I shoot my loads in the winter and summer which is a 70 degree spread (40 to 110 degrees) without adjustment.
Thanks for the quick response German. I may give this powder a try in my 6.5×47.
I have used this powder with great results behind 190 sierras/berger vlds and 185 bergers naked and moly in my M1 Garand. I used LC brass, Winchester and CCI Primers, started at 44.0gr. .006-.008 into the lands. This was an old recipe when the Navy was doing well with the M1. Give this powder a chance.
Excellent information, analysis and very timely! I currently have enough Varget for the next yr or so worth of Palma loads but I’m going to have a serious look at this powder if this shortage continues. Thanks very much.
Shhh! Don’t tell anyone else about 4320.
For many years the Navy used used imr- 4320 behind the 190 Sierra for thier 308 long range load, it worked realwell in M1’s without damage to the op rod. I was the coach and firing member of the Navy Reserve Rifle Team.
For many years a friend used this powder in his .223 bolt gun with 69 grain MK’s
He beat me like a drum from 100-200 yards.
He finally told me his secret recipe when he retired from shooting years later.
I used 4320 in 6.5×55 loads with excellent results. One Model 96 would do 3/4″ at 100yds with 4320 and 140gr SMKs or 140gr Game Kings.
That barrel was rough as a cob and was no fun to clean but, still produced excellent accuracy. That was my first centerfire rifle costing $59 and my first rifle caliber to handload. Only Norma factory ammo was generally available at $20+ per box so, I bought three boxes costing as much as the rifle. Loaded those cases many times.
4320 has worked well in all the rifles I’ve tested it with. 45-70govt, 375H&H, 300 win-mag, and 270 bullets ranging from 140-400 gr. I can pin down a 300 yard soda can with my 45-70 shooting a 400gr barnes bullet with a good dose of propellant. doesn’t seem too picky bout the charge either, just has to be close to max to shoot real tight.
what load of imr4320 would work in a 270 with 150gr boat tail?
como funciona en el .243 Win.
How’s it in a Garand with 150s and 168s, and what grs would be used
Mr Salazar,
I’d love to read your article on IMR 4320 in Riflemans Journal Blog but it seems I have to be invited. Why are the links published as active? Thank you,
Elvio Marchi
Editor: The story you read is five years old. We are not able to chase down every old link. There are over 8000 Bulletin stories, many with a half-dozen or more links.
I use IMR 4320 in my 308 Savage Stealth, I use mostly 168 grain bullets, 45 grains and it shoots pretty tight groups
I have a custom built 358 Norma Mag that loves this powder, 3/4″ 5 shot groups all day long.
I’m using this powder for 223, 308 and 458 Lott. I wish it was suitable for 375 Ruger as well and I would use it in that. It’s been very available anywhere I go.
Looking for reload data for IMr 4320 Please help
I have a Sako Alaskan Hunter. It was a special run some 25 years ago that has a 20″ barrel. In the process of trying to find a powder for the 200 grain Speer bullet with less muzzle blast I tried 4320. Accuracy is amazing. I don’t have a chronograph but testing showed it has about the same trajectory as a 180g bullet from a 30-06. Yes there is still some muzzle blast but no where near as much as factory.