Have you tried IMR Enduron powders yet (IMR 4166, 4451, 4955, 7977, and/or 8133)? We’ve been impressed with what we’ve seen. IMR’s line of Enduron extruded powders offer excellent temp stability, reduced copper fouling, and good load density for many popular cartridges (such as .223 Rem, 6mmBR, .308 Win, .30-06, 300 WSM to name a few). Some of our Forum members have reported excellent results with IMR 4166 in the 6mmBR, Dasher, 6.5×47 Lapua and .308 Win. One member wrote: “in my 6.5×47… 4166 gives speeds and accuracy pretty much exactly the same as Varget.” And other shooters have observed reduced copper fouling with Enduron series powders, so IMR’s Enduron anti-fouling chemistry does seem to work.
IMR now offers five (5) Enduron powders: IMR 4166, IMR 4451, IMR 4955, IMR 7977, and IMR 8133. Shooters looking for good alternatives to hard-to-find extruded powders should definitely check out the Enduron line-up. Precision shooters will find an Enduron option well-suited to most popular precision cartridge types. For example, IMR 4166 is a good replacement for Hodgdon Varget (commonly used in the .223 Rem, 6mmBR and .308 Win), while IMR 4955 is a fine substitute for H4831 (favored by F-Open shooters for the .284 Win and 7mm WSM cartridges).
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 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 is a slower burn rate in the Enduron family. Loading density is perfect for magnums. This is a true magnum propellant yielding outstanding performance in .300 Winchester Magnum, 7mm Remington Magnum and .338 Lapua Magnum. IMR 7977 is comparable to Hodgdon H1000.
IMR 8133 IMR Enduron 8133 is the slowest burn rate in the Enduron family. Loading density is perfect for the very large magnums, including the 6.5mm and 7mm magnums. This is a true magnum propellant yielding outstanding performance in 6.5-300 Weatherby, .264 Win Mag, 28 Nosler and .300 Rem Ultra Mag, among other cartridges.
IMR Enduron Technology powders are sold in one-pound (1 lb) and eight-pound (8-lb) containers through quality retailers including Graf & Sons, Midsouth, and Powder Valley. Check frequently for current availability as these will sell out quickly after arrival. Also check your local sporting goods dealers for recent powder shipments.
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Have you tried IMR Enduron powders yet (IMR 4166, 4451, 4955, and 7977)? We’ve been impressed with what we’ve seen. IMR’s line of Enduron extruded powders offer excellent temp stability, reduced copper fouling, and good load density for many popular cartridges (such as .223 Rem, 6mmBR, .308 Win, .30-06, 300 WSM to name a few). Some of our Forum members have reported excellent results with IMR 4166 in the 6mmBR, Dasher, 6.5×47 Lapua and .308 Win. One member wrote: “in my 6.5×47… 4166 gives speeds and accuracy pretty much exactly the same as Varget.” And other shooters have observed reduced copper fouling with Enduron series powders, so IMR’s Enduron anti-fouling chemistry does seem to work.
Varmint hunters, big game hunters, match shooters and military snipers all seek powders that are insensitive to temperature changes. These powders all have it. This translates to point of impact and group size remaining the same, no matter what temperature conditions prevail. Another huge benefit is an additive that prevents copper fouling from building during dozens of rounds being fired. Here the advantage is top accuracy for longer periods of time, and less cleaning time.
A third major accomplishment with this technology is ideal load density. Experienced reloaders know that a case-filling load often delivers the most uniform velocities and best accuracy. We see this in popular match cartridges such as the 6PPC, 6mmBR, 6BRA, 6.5 Creedmoor and .308 Win. These new Enduron powders offer excellent “full case” load density for the most commonly used cartridges with popular bullets.
These three powders, IMR 4166, IMR 4451 and IMR 7977, are environmentally friendly by not having any ingredients harmful to the environment. Add to that, the three of them cover the most popular cartridges from .204 Ruger up to the mighty 500 Nitro Express, and the handloader “has it all”.
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Winchester has just introduced a new ball propellant, StaBALL 6.5, which it claims is very temp-stable. This means velocities and pressures should not vary greatly across a wide range of ambient temperatures. Winchester states: “StaBALL 6.5 is the world’s first temperature-insensitive Ball Powder, stable in extreme-hot or extreme-cold temperatures.” Winchester also claims StaBALL 6.5 can offer 30-200 fps greater velocities than other powders with similar burn rates. This new powder also has additives to reduce copper fouling. StaBALL 6.5’s burn rate and load density is good for popular cartridges such as .223 Rem, 6mm Creedmoor, 6.5×47 Lapua, 6.5 Creedmoor, and .270 Win. If StaBALL 6.5 can really deliver excellent metering, temp stability, more speed, AND less fouling — Winchester could really have a winner.
Metering Advantages of Ball Propellants
As there are existing very temp-stable extruded powders, such as Reloder 16 and H4350, what’s the big deal here? Well ball powders, with their small spherical granules, flow easily and meter well. This means ball powders can be thrown in manual powder measures with great precision. So StaBALL 6.5 could have advantages for hand-loaders using manual powder measures or progressive presses with mechanically-operated charge dispensers.
Reloading Data is ONLINE Now
Reloading Data is NOW Available on the Winchester website for a wide variety of cartridges including: 22 Nosler, .223 Rem, 224 Valkyrie, 22-250 Rem, 6GT, 6×47 Lapua, 6mm Creedmoor 6.5×47 Lapua, 6.5 Creedmoor, .260 Rem, .270 Win, 7mm-08, .30-06, 300 WSM and more. To get official LOAD DATA, scroll below the product description, select a cartridge type, and then click the RED “Get Reloading Data” tab. Here are two of 13 listed load options (55-115 grain bullets) for the 6mm Creedmoor:
StaBALL 6.5 is the world’s first temperature-insensitive BALL® Powder, stable in extreme-hot or -cold conditions. It provides optimal loading density in cartridges appropriate for the burn speed, which is ideal for 6mm Creedmoor, 6GT, 6.5 Creedmoor, 7MM-08, .270 Winchester, and many more.
Typical of a ball powder, precise metering contributes to improved velocity and pressure standard deviations, ingredients that are paramount to match grade accuracy!
This “environmentally green” propellant has copper fouling reducer additives, meaning longer durations of competition and field shooting without having to clean the bore. Precision accuracy throughout the match!
Velocity levels obtainable, depending on the cartridge, are 30-200 fps greater than other propellants in its class.
StaBALL 6.5 powder is available in 1 lb. and 8 lb. containers.
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This article, in longer form, appears on the USAMU Facebook page, as part of the “Handloading Hump Day Series”. This article explores three different “Philosophies” of precision reloading. Some handloaders seek to produce ammo that yields the very tightest groups (without factoring in the wind). Other shooters load their ammo to deliver the highest safe velocity. That’s because a projectile launched at higher velocity will drift less in the wind. The theory is that even if fast ammo doesn’t produce the tightest groups in zero wind conditions, it will yield higher scores in a the real world (where the wind blows). Lastly, some handloaders favor ammo that is ultra-consistent across a wide temperature range. This last philosophy dictates selection of a powder that is temp-insensitive, even if it may not produce the very best raw accuracy (or speed).
What’s Your Handloading Philosophy?
Objectives of Reloading — Accuracy, Velocity, Temp Stability What do you, the reader, primarily value in your handloads?
Viewpoint ONE: Accuracy Trumps Everything
Some shooters prize consistent, excellent medium/long range accuracy enough that they’re willing to give up some extra velocity (and reduced wind deflection) to obtain that. Their underlying philosophy could be stated: “Superior accuracy is present for every shot, but the wind isn’t”. One’s ability to hold well, aim well and read the wind are all factors in making this type decision. The photo below shows stellar raw accuracy. This is an 0.67″, 10-shot group at 300-yards fired from a text fixture. The group measures just 0.67″. (This shows the USAMU’s 600-yard load with 75gr bullets).
Viewpoint TWO: Load to Highest Safe Velocity for Less Wind Drift
Some shooters value obtaining the highest safe velocity, even if one’s pure, consistent mechanical accuracy at medium/long range isn’t quite as brilliant. The theory here seems to be that a really good hold extracts as much mechanical accuracy from the rifle/ammo as possible, and faster bullets equal occasional “bonus” points snatched from the jaws of wind.
[For example] one of the USAMU’s many Service Rifle National Champions revealed his philosophy. It can be stated thus: a super-accurate, but [relatively] “slow” load “required him to have a Ph.D. in wind reading for every shot, while a faster, but less accurate load netted him more points.”
Note — this was not mere speculation; his score book data backed up his claims, due to less wind effects. Remember, however, this fellow has a consistent, National Championship-level hold, and other Champions on the same team would have opted differently.
Viewpoint THREE: Temperature Stability Is Key
Still another approach is to place heavy emphasis on fine accuracy with absolute stability in changing temperatures. When this writer was actively earning his Distinguished Rifleman badge, that was his goal. The reason? Sighting shots are not allowed in EIC (“Leg”) matches. The first shot out of the barrel was for score. It had to be 100% consistent, with very reliable, predictable elevation and wind deflection regardless of the ambient temperature — even if it wasn’t the lowest wind deflection possible.
Naturally, selecting a powder that is insensitive to temperature changes is a key element here. Elevation zeros and wind effects HAD to be consistent every time. Hunters and military snipers might be among those who fall into this camp, as well as those in pursuit of their Distinguished Rifleman badges.
Contrast that with a traditional High Power shooter who gets two sighter shots before each event (offhand, sitting rapid, prone rapid, prone slow fire.) If there is a zero change on any given day, he/she can correct during sighters. This writer well remembers talking with another very high-level Service Rifle competitor who was happy to have high temperatures boost the velocities of his ammunition above their usual level… As far as this SR competitor was concerned, 60-80 fps more velocity -– even if only due to high ambient temperatures -– meant less wind deflection, and he was mighty happy to have it.
Particularly in the summer, with hot daily conditions, you need to be concerned about temperature stability. Loads worked up in winter may not work in the summer time.
This article has been confined to NRA High Power Rifle competition, which has relatively generous 10-ring dimensions in relation to the accuracy of well-built competition rifles. Hopefully, it will provide food for thought. For some, this might be an opportunity to ensure that one’s load development approach helps them attain their desired results.
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Alliant is now shipping an advanced medium-fast burn rate pistol powder that has many important qualities. New Sport Pistol powder exhibits excellent temp stability. That means you can develop a stout load and not worry about hot days at the range. Sport Pistol was also formulated to work with the new generation of polymer-coated bullets. Alliant’s engineers tell us: “This new propellant is very advanced. The chemistry of Sport Pistol is not similar to Bullseye or other older pistol powders. Sport Pistol delivers precise performance with all bullet types, but the low muzzle-flash formulation was optimized for polymer-coated bullets. Other double-base powders can dissolve the polymer coatings at the bullet base, and this exposes the lead to vaporization due to the intense heat during the ballistic cycle.” Alliant says this powder burns clean and gives “extremely reliable cycling, excellent charging/case fill [with] ballistics that lend themselves to a range of popular loads.”
How Sport Pistol Compares to Other Pistol Powders
It looks like Alliant’s new Sport Pistol can be used to replace W231 and HP-38, two popular powders for 9mm, .40 S&W, and .45 ACP cartridges. One pistolero notes: “Just looking at the load data for Sport Pistol, charge weights are similar to W231/HP-38 and Alliant advertises it as ‘medium fast’ burning for precision and action shooting competition. I say Alliant released a competing powder for W231/HP-38 that is less temperature sensitive.”
PrecisionRifleBlog.com (PRB) recently published results from a field test PRB conducted to quantify the temperature stability of the popular Hodgdon H4350 and Varget powders and compare those to IMR’s new Enduron line of powders, specifically IMR 4166 and 4451.
Hodgdon Extreme Series powders have attracted quite a fan base, with over 90% of the top shooters in the Precision Rifle Series choosing to run one of those powders. IMR recently released a new line of powders “with Enduron Technology” — which is also marketed to have “extreme temperature stability”. Sounds familiar! These new powders should compete directly with the Hodgdon Extreme Series, which gives shooters more temp-stable powder options to consider.
The top shooters in the PRS and veteran long-range shooters in other disciplines have learned to value a temperature-stable powder. That’s because a change in temperature can affect the trajectory or “flight path” of the bullet in two well-known ways:
1. Assuming all other environmental conditions remain the same, an increase in air temperature will cause a flatter trajectory due to a lower air density (easier for the bullet to cut through the air).
2. The same increase in temperature also causes the nitrocellulose-based powder inside the cartridge to burn at a higher rate, producing approximately four times the Point of Impact (POI) shift than just air temperature alone. (SEE: Temperature Effects On Zero on KestrelMeters.com.)
“The initial heat condition of your powder will affect the burn rate,” Bryan Litz explained at a recent Applied Ballistics Seminar. That means swings in ambient outside temperature can affect your internal ballistics, which will directly affect your muzzle velocity, which will change your bullet’s trajectory. Some powders are more affected by changes in temperature than others. So if your goal is first-shot hits and you may shoot in a variety of conditions — you should care about temperature stable powders.
The folks at PrecisionRifleBlog.com meticulously loaded 6.5×47 Lapua ammo with each powder using some of the best equipment available. This included the top-of-the-line Prometheus Gen II Powder Scale, which is capable of loading to the nearest kernel of powder. This ensured the powder charges were identical for each round of ammo. PRB’s testers explain the full set of equipment and steps in their loading process in the Full Test Report.
Once they had a couple dozen rounds loaded with each powder, they went and shot them with each powder at 25° F, 65° F, and 140° F. The muzzle velocity of each shot was recorded using both a LabRadar Doppler Radar and a MagnetoSpeed Chronograph. The LabRadar is a new type of device that allows you to measure muzzle velocity within at least +/- 0.1% of the reading.
Here are the results from the PRB Powder Temp Stability Tests:
You can see Hodgdon H4350 had the least variance in muzzle velocity, with just 25 fps over the 115° swing in temperature! That is very, very low. Hodgdon Varget was the second least temperature sensitive powder in this test, with 46 fps of variance in muzzle velocity between temperatures of 25° F and 140° F. IMR 4166 performed very similar to Varget, and proved to be fairly insensitive to large swings in temperature. IMR 4451 had the largest swing in muzzle velocity of the powders tested, but keep in mind just 68 fps over 115° F swing is still a good performance.
Most powders aren’t specially formulated to be temperature stable. So they would likely show much larger swings than what these four top-performing powders showed.
PRB’s test team also noticed other interesting trends in the data. For example, variation in velocity does NOT appear to be linear across the full range of temperatures. By that, they mean the change per degree from 20° to 65° might be smaller or larger than the change per degree from 65° to 140°.
