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March 18th, 2020
 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 considerably 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, GS Arizona wrote an excellent Riflemans Journal article, IMR 4320 — the Forgotten Powder. GS developed IMR 4320 loads for his .308 Win Palma rifle and competed with IMR 4320-powered ammo at long range matches. He 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 |
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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
IMR 8208 XBR is also good — if you can find it
Another good substitute for Varget powder in a .223 Rem or .308 Winchester is IMR 8208 XBR. In our own .308 Win tests, this generated slightly more velocity than Varget, with good ES/SD. However, this very good IMR 8208 XBR powder is out-of-stock at many vendors.
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September 13th, 2015
In response to our Bulletin story about the availability of Norma powders at Midsouth Shooters Supply, one of our Forum members asked: “I’m having trouble finding Reloder 15 for my 6.5×47 Lapua — should I consider running Norma 203B instead?” As we’ve explained before, these two powders, both made by Bofors in Europe, are very, very similar. Here are some hard numbers that should demonstrate how virtually identical these powders really are.
Target Shooter Magazine writer Laurie Holland compared Norma 203B and Reloder 15 using data from QuickLOAD. Laurie also checked load manuals to see how listed charge weights varied for the two propellants. Laurie concluded there was very little difference between Norma 203B and Reloder 15.
 Norma 203B vs. Alliant Reloder 15
Commentary by Laurie Holland
Running [203B and RL15] through QuickLOAD doing a ‘charge table’ run for a 130gn Berger VLD at 2.700 COAL in 6.5X47 Lapua, gives very similar positions in the table [for both powders]. The charge required to achieve 62,000 psi estimated pressure varies by a mere 0.2 grains between the pair, Norma 203B being the heavier of the two. The estimated Muzzle Velocity (MV) also varies by a mere 2 fps, RL15 estimated to produce 2,946 fps MV compared to 2,944 fps for N203B at 62,000 psi (with the parameters I used).
If they aren’t the same thing, they’re so close as to make no difference and as Forum Boss points out, they’re made by the same people (Bofors) in the same plant.
[The Berger Reloading Manual includes data for both powders] for the .308 Winchester and heavier bullets (185 to 230 grains). Maximum charges and claimed MVs are not always identical, but are so close as to be marginally different production lots of the same thing, or maybe the result of minor testing variations.
.308 Win Max Charge Weights in Grains (RL15 / N203B) (Berger Manual)
MVs [for the four bullet types] are close but not identical, the largest difference being for the 210s which shows RL15 producing 2,428 fps MV v 2,383 for Norma 203B.
Norma 203B Chemistry
According to the Norma Reloading Handbook #1, Norma 203B has the following composition:
85% Nitrocellulose
7.5% Nitroglycerin
2.0% surface coating
4.6% Various chemicals
0.9% Water
3,957 J/g specific energy
890 g/l specific density
For comparison, the 7.5% NG component compares to 15% in Viht N500 series powders and 10% in Ramshot TAC / Big Game / Hunter.
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March 1st, 2011
 Here’s the latest info on Alliant’s new AR-Comp powder. We had a chance to talk with Dick Quesenberry of Alliant, who revealed more details about this new propellant. First, Dick explained that AR-Comp is an advanced re-formulation of Reloder 15, a double-base Bofors powder. There are changes to internal and external chemistry to provide much better pressure/velocity stability across a wide range of temperatures.
AR-Comp Offers Uniform Velocities over a Wide Temp Range
Tests were done with .223 Rem and .308 Win ammo, loaded with AR-Comp and maintained at temps from -20° F to +160° F in a controlled test center. The ammo itself was heated or cooled to targeted temps before testing. Across that entire range of temperature, -20° F to +160° F, the ammo loaded with AR-Comp showed a variation of only 20 fps in muzzle velocity. The primary bullet type tested was a 77gr .224 bullet and the secondary was a 175gr .308 bullet.
Burn Rate Like Varget: Though this is a reformulation of Reloder 15, the burn rate of AR-Comp is slightly faster than Reloder 15. Alliant told us: “Reloder 15 is slightly slower, in burn rate, than Varget. The new AR-Comp, with the enhancements, ended up slightly faster than Reloder 15, so it is now very close to Varget in burn rate”. This is the result of the “tuning” of the powder to be much less temp-sensitive.
Meters Like Reloder 15: AR-Comp is a small-kernel, double-base extruded powder like Reloder 15, so it will continue to meter just like Reloder 15. The load density should be the same as Reloder 15.
Loaded Ammo: We asked if any manufacturer will be using AR-Comp in loaded ammo. Dick told us that he is “not allowed to release that information at this time”. Draw your own conclusions, but remember that Alliant is owned by ATK, which makes Federal rifle ammo.
Available in Summer 2011: Allliant hopes to ship AR-Comp in “June or July” of 2011, provided the DOT Classification process moves at a normal schedule. The powder is ready to go, Alliant is just waiting on the DOT to provide shipping authorization.
Reloder 15 Will Stay in Production: Fans of Alliant’s Reloder 15 don’t need to worry. Alliant will keep Reloder 15 in production. “We don’t drop powder lines”, said Quesenberry.
AR-Comp First in Series of New Alliant Temp-Stable Powders
Alliant has been working on AR-Comp for quite some time. This represents a major evolution for Alliant’s powder line. AR-Comp will be the first in a series of “new generation” temp-stable powders from Alliant. Quesenberry noted: “Our goal was to provide a powder that offers stable pressures in all temperatures. Shooters want to be able to stay with the same load in winter and in summer, in cold or in hot conditions.”
Quesenberry added: “We’ve been working on this quite a while. AR-Comp is the first example and we hope to extend this to other rifle powders. It’s a tough job. You have to balance the performance carefully. If you tweak it one way, say to improve the low temp performance, you lose something at the upper end. If you tweak it for the top end, you loose something at the bottom. You have to hit that balance. We worked very hard to do just that and we think shooters will be impressed with the results.”
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April 22nd, 2010
The 6mm Dasher is based on the 6mm BR cartridge with the shoulder blown forward about 0.100″ and “improved” to 40°. Case capacity is raised to about 41.0 grains. This allows the Dasher to drive 105-108gr bullets comfortably at 2970-3000 fps without over-stressing the brass. A popular load used by many successful Dasher shooters is 33.3 grains of Reloder 15, CCI 450 primers, with 105gr Berger VLDs, .010″ in the lands. This is a “warm load” and should only be used with fire-formed brass. As with any load, start 10% low and work up. You may also have good luck jumping the bullets .020″ or more.
Robert Hoppe, one of the top 600-yard shooters in the country, was the 2009 NBRSA 600-yard champion. In 2007, shooting a 6 Dasher, Robert nailed a 0.5823″, 5-shot group. At the time it was the smallest group ever shot in 600-yard registered benchrest competition. In 2008, John Lewis shot even smaller with an IBS Heavy Gun, but Robert’s 0.5823″ still remains the NBRSA 600-yard record, and we believe it is the smallest group ever shot at 600 (in registered BR competition) by a 17-lb class rifle. Robert has been very successful in the 600-yard game, and is one of the best 600-yard shooters in the West. He knows how to wring the best accuracy out of the 6mm Dasher cartridge. Here Robert offers some tips on load development and tuning for the 6mm Dasher.
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March 27th, 2009
The 6mm Dasher is based on the 6mm BR cartridge with the shoulder blown forward about 0.100″ and “improved” to 40°. Case capacity is raised to about 41.0 grains. This allows the Dasher to drive 105-108gr bullets comfortably at 2970-3000 fps without over-stressing the brass. A popular load used by many successful Dasher shooters is 33.3 grains of Reloder 15, CCI 450 primers, with 105gr Berger VLDS, .010″ in the lands. This is a “warm load” and should only be used with fire-formed brass. As with any load, start 10% low and work up. You may also have good luck jumping the bullets .020″ or more.
Robert Hoppe is one of the top 600-yard shooters in the country. Last fall, shooting a 6 Dasher, Robert nailed a 0.5823″, 5-shot group. At the time it was the smallest group ever shot in 600-yard registered benchrest competition. Just last weekend, John Lewis shot even smaller with an IBS Heavy Gun, but Robert’s 0.5823″ still remains the NBRSA 600-yard record, and the smallest group ever shot at 600 by a 17-lb class rifle. Robert has been very successful in the 600-yard game, and he finished 5th recently at the NBRSA 600-yard competition. He knows how to wring the best accuracy out of the 6mm Dasher cartridge. Here Robert offers some tips on load development and tuning for the 6mm Dasher.
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