November 12th, 2017

IMR Enduron 8133 — New Slow-Burn-Rate Magnum Powder

IMR Enduron Powders 8133 4955 4451 4166 7977

IMR, a Hodgdon Powder Company brand, will soon release a new, slow-burn-rate magnum powder, IMR Enduron® 8133. This new powder is designed for large, magnum cartridges, such as .300 Win Magnum, .300 Remington Ultra Magnum, and 28 Nosler, among others. With the slowest burn rate among Enduron powders, 8133 has burn properties similar to Hodgdon Retumbo. The new Enduron 8133 powder will be available in 1-lb and 8-lb canisters starting in February 2018. Load Data for this new powder is already listed on the Hodgdon Reloading Data Center.

CLICK HERE for IMR Enduron 8133 Reloading Data »

IMR® Legendary Powders now offers five (5) Enduron powders: IMR 4166, IMR 4451, IMR 4955, IMR 7977, and IMR 8133. “It was always our intent to fill out the Enduron line with a magnum powder and we could not be happier with how 8133 performed in development and testing,” says Ron Reiber, Hodgdon ballistician. “This powder delivers the [slow burn rate] magnum-caliber reloaders require and adds all of the performance characteristics of the Enduron line of powders”. These qualities include temp stability, significantly reduced copper fouling, and optimal load density.

Modern Powder Technology for Enhanced Performance

IMR Enduron Powders 4955 4451 4166 7977

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 Five Powders

IMR now offers FIVE 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 Enduron Powders

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 second slowest burn rate among the Enduron Technology powders. It yields great performance in .300 Winchester Magnum, 7MM Remington Magnum, and .338 Lapua Magnum. IMR 7977 is comparable to Hodgdon H1000.

IMR 8133 is designed specifically for magnum calibers, such as .300 Remington Ultra Magnum, 28 Nosler, or the .264 Winchester Magnum, among many others. This new powder has the slowest burn rate among the Enduron powders and compares in burn rate to Hodgdon Retumbo.

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July 4th, 2017

How Ammo Temp Affects Pressure, Velocity, and Point of Impact

Sierra Bullets Ammunition Ammo temperature temp test hot F-Class Ammo cold
In this .308 Win test, 70° F ammo shot 96 FPS slower than ammo heated to 130.5° F. And the 130.5° ammo was 145 fps faster than ammo right out of the freezer (at 25.5° F). That’s a huge difference…

EDITOR’s NOTE: The Sierra tester does not reveal the brand of powder tested here. Some powders are much more temp sensitive than others. Accordingly, you cannot extrapolate test results from one propellant to another. Nonetheless, it is interesting to see the actual recorded velocity shift with ammo temperature variations in a .308 Win.

Written by Sierra Chief Ballistician Tommy Todd
This story originally appeared in the Sierra Bullets Blog
A few weeks ago I was attending the Missouri State F-Class Match. This was a two-day event during the summer and temperatures were hot one day and hotter the next. I shot next to a gentleman who was relatively new to the sport. He was shooting a basically factory rifle and was enjoying himself with the exception that his scores were not as good as he hoped they would be and he was experiencing pressure issues with his ammunition. I noticed that he was having to force the bolt open on a couple of rounds. During a break, I visited with him and offered a couple of suggestions which helped his situation somewhat and he was able to finish the match without major issues.

He was shooting factory ammunition, which is normally loaded to upper levels of allowable pressures. While this ammunition showed no problems during “normal” testing, it was definitely showing issues during a 20-round string of fire in the temperatures we were competing in. My first suggestion was that he keep his ammunition out of the direct sun and shade it as much as possible. My second suggestion was to not close the bolt on a cartridge until he was ready to fire. He had his ammo in the direct sunlight and was chambering a round while waiting on the target to be pulled and scored which can take from a few seconds to almost a minute sometimes.

This time frame allowed the bullet and powder to absorb chamber [heat] and build pressure/velocity above normal conditions. Making my recommended changes lowered the pressures enough for the rifle and cartridge to function normally.

Testing Effects of Ammunition Temperature on Velocity and POI
After thinking about this situation, I decided to perform a test in the Sierra Bullets underground range to see what temperature changes will do to a rifle/cartridge combination. I acquired thirty consecutive .30 caliber 175 grain MatchKing bullets #2275 right off one of our bullet assembly presses and loaded them into .308 Winchester ammunition. I utilized an unnamed powder manufacturer’s product that is appropriate for the .308 Winchester cartridge. This load is not at the maximum for this cartridge, but it gives consistent velocities and accuracy for testing.

I took ten of the cartridges and placed them in a freezer to condition.

Sierra Bullets Ammunition Ammo temperature temp test hot F-Class Ammo cold

Sierra Bullets Ammunition Ammo temperature temp test hot F-Class Ammo cold

I set ten of them on my loading bench, and since it was cool and cloudy the day I performed this test I utilized a floodlight and stand to simulate ammunition being heated in the sun.

Sierra Bullets Ammunition Ammo temperature temp test hot F-Class Ammo cold

I kept track of the temperatures of the three ammunition samples with a non-contact laser thermometer.

The rifle was fired at room temperature (70 degrees) with all three sets of ammunition. I fired this test at 200 yards out of a return-to-battery machine rest. The aiming point was a leveled line drawn on a sheet of paper. I fired one group with the scope aimed at the line and then moved the aiming point across the paper from left to right for the subsequent groups.

NOTE that the velocity increased as the temperature of the ammunition did.

The ammunition from the freezer shot at 2451 fps.

Frozen FPS

The room temperature ammunition shot at 2500 fps.

Room Temperature FPS

The heated ammunition shot at 2596 fps.

Sierra Bullets Ammunition Ammo temperature temp test hot cold

The tune window of the particular rifle is fairly wide as is shown by the accuracy of the three pressure/velocity levels and good accuracy was achieved across the board. However, notice the point of impact shift with the third group? There is enough shift at 200 yards to cause a miss if you were shooting a target or animal at longer ranges. While the pressure and velocities changed this load was far enough from maximum that perceived over pressure issues such as flattened primer, ejector marks on the case head, or sticky extraction did not appear. If you load to maximum and then subject your ammunition to this test your results will probably be magnified in comparison.

Sierra Bullets Ammunition Ammo temperature temp test hot cold

This test showed that pressures, velocities, and point-of-impact can be affected by temperatures of your ammunition at the time of firing. It’s really not a bad idea to test in the conditions that you plan on utilizing the ammo/firearm in if at all possible. It wouldn’t be a bad idea to also test to see what condition changes do to your particular gun and ammunition combination so that you can make allowances as needed. Any personal testing along these lines should be done with caution as some powder and cartridge combination could become unsafe with relatively small changes in conditions.

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July 1st, 2017

Smarter Shooter: Keep Your Ammo Cool on Hot Summer Days

Heat Map USA color chart

Well folks, it’s July 1st already — the means we’re moving into “peak heat” summer conditions. It’s vitally important to keep your ammo at “normal” temps during the hot summer months. Even if you use “temp-insensitive” powders, studies suggest that pressures can still rise dramatically when the entire cartridge gets hot, possibly because of primer heating. It’s smart to keep your loaded ammo in an insulated storage unit, possibly with a Blue Ice Cool Pak if you expect it to get quite hot. Don’t leave your ammo in the car or truck — temps can exceed 140° in a vehicle parked in the sun.

Ammo cool storage

Bosch Insulated tool caseTo learn more about how ambient temperature (and primer choice) affect pressures (and hence velocities) you should read the article Pressure Factors: How Temperature, Powder, and Primer Affect Pressure by Denton Bramwell. In that article, the author uses a pressure trace instrument to analyze how temperature affects ammo performance. Bramwell’s tests yielded some fascinating results.

For example, barrel temperature was a key factor: “Both barrel temperature and powder temperature are important variables, and they are not the same variable. If you fail to take barrel temperature into account while doing pressure testing, your test results will be very significantly affected. The effect of barrel temperature is around 204 PSI per F° for the Varget load. If you’re not controlling barrel temperature, you about as well might not bother controlling powder temperature, either. In the cases investigated, barrel temperature is a much stronger variable than powder temperature.”

Powder Heat Sensitivity Comparison Test

Cal Zant of the Precision Rifle Blog has published a fascinating temp-stability comparison test of four powders: Hodgdon H4350, Hodgdon Varget, IMR 4451, and IMR 4166. The first two are Hodgdon Extreme powders, while the latter two are part of IMR’s new Enduron line of propellants.

CLICK HERE to VIEW FULL TEST RESULTS

The testers measured the velocity of the powders over a wide temperature range, from 25° F to 140° F. Hodgdon H4350 proved to be the most temp stable of the four powders tested.

Precision Rifle Blog Temperature Stability test hodgdon varget H4350 Enduron IMR 4451

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August 19th, 2016

New Temp-Stable Alliant Reloder 16 Now Available

Reloder Reloader 16 Alliant Powder Propellant Bofors TZ temperature stability temp stable H4350

Here’s an important announcement for anyone who uses a powder in the 4350 range. Alliant is now shipping the all-new Reloder 16 powder. The burn rate is slightly faster than Reloder 17, and a bit slower than Varget or Reloder 15. Notably, this new Reloder 16 powder is very temp stable. AccurateShooter.com was shown “top secret” test results comparing Reloder 16 with other popular propellants, including Hodgdon Extreme series powders. The results for Reloder 16 were remarkable. Reloder 16 showed extremely constant velocities even with very high ambient temps — so this is a powder you can shoot even on hot Arizona summer days.

CLICK HERE for Reloder 16 Suggested Load Recipes

This is NOT just a slower version of Alliant’s double-based Reloder 15 (which words great in the 6mmBR and Dasher cartridges). Reloder 16 is a completely new formulation, produced in Sweden by Bofors for Alliant. Reloder 16 utilizes TZ technology, which manipulates the response of the propellant and resists the natural tendency to generate more pressure at higher temperatures and less pressure at lower temperatures.

Reloder Reloader 16 Alliant Powder Propellant Bofors TZ temperature stability temp stable H4350

As a result, Reloder 16 offers outstanding temperature stability. Based on the test results we’ve seen, if you are using H4350 or IMR 4451 currently, you should definitely give Reloder 16 a try. The powder also boasts excellent lot-to-lot consistency and contains a proprietary de-coppering additive.

Reloder Reloader 16 Alliant Powder Propellant Bofors TZ temperature stability temp stable H4350

Match and Hunting Cartridge Applications:
Alliant tells us that Reloader 16 “is ideal for traditional hunting cartridges, such as .30-06 Springfield and .270 Winchester, as well as 6.5mm target loads and tactical applications wherein temperature stability is required.” We also think the powder may work very well in these popular match cartridges: 6XC, .243 Win, 6.5×47 Lapua, 6.5 Creedmoor, .260 Rem, .284 Win, and .300 WSM. For example, Alliant’s Load Data Sheet shows a 2772 FPS load with 142gr SMKs in the .260 Rem.

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