Today, June 20, 2024 is Summer Solstice, the longest day of the year. And right now the Northeast USA is undergoing a major heatwave. That means “peak heat” summer conditions have arrived already. 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.
The way ambient temperatures, barrel heating, and powder warming can affect cartridge pressures (and hence velocities) was covered in a study Pressure Factors: How Temperature, Powder, and Primer Affect Pressure by Denton Bramwell. In that article, the author used 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.”
This Editor had the personal experience of 6mmBR hand-loaded ammo that was allowed to sit in the hot sun for 45 minutes while steel targets were reset. The brass became quite warm to the touch, meaning the casings were well over 120° on the outside. When I then shot this ammo, the bullets impacted well high at 600 yards (compared to earlier in the day). Using a Magnetospeed, I then chron-tested the sun-heated ammo. The hot ammo’s velocity FPS had increased very significantly — all because I had left the ammo out in the hot sun uncovered for 3/4 of an hour.
LESSON: Keep your ammo cool! Keep loaded ammo in the shade, preferably under cover or in an insulated container. You can use a SEALED cool pack inside the container, but we do NOT recommend H20 ice packs. And don’t have the container do double duty for food and beverages.
Powder Heat Sensitivity Comparison Test
Our friend Cal Zant of the Precision Rifle Blog has published a fascinating 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 Enduron line of propellants.
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. [NOTE: New Alliant Reloder TS 15.5 has also proved very temp stable in AccurateShooter’s range tests.]
What’s a “Wallet Group”? It’s a singularly spectacular proof target that entitles its bearer to bragging rights. The wallet group may or may not have been shot in competition, and, by definition, it may not be repeatable. But it exists as incontrovertible proof that, at least once, the stars aligned, and the wind gods smiled on the shooter.
Five Shots in 0.178 MOA at 1000 Yards
A few years ago, Forum member and F-Class shooter Gary Wood was testing his 6.5-284 rifle at the 1000-yard range in Coalinga, California, getting ready for an upcoming long range match. In practice, Gary nailed a witnessed 1.859″ five-shot group, with four of the five shots well under an inch. Use this as proof to win those club-house arguments about whether it is possible to shoot “in the ones” at 1000 yards. Gary’s group worked out to 0.178 MOA!
Gary reports: “I was load testing with 5-shot groups. Each group was shot on a new F-Class center and pulled by Ret. Master Chief Jerry Pullens and spotted by an other long-range shooter. The second 5-shot load group looked really small … by our reckoning four out of five shots measured under an inch. I was amazed. What’s more, when I shot the group, the 4th shot blew the spindle out of the 3rd shot. My spotter saw that in his scope and Jerry Pullens told me about it afterwards”.
As measured with the OnTarget Software, using a scan of the target, Gary plotted the group size at 1.859″ total for five shots, or 0.178 MOA. Gary noted: “I had everyone sign the target which I saved and photographed.” Yes, Gary, this may be the wallet group to end all wallet groups. You should have that target framed.
Gary’s Load and 6.5-284 Rifle Specs
Gary was running a stout load of Hodgdon H4350 and CCI BR-2 primers, pushing moly-coated 142gr Sierra MKs, in Lapua 6.5-284 brass. The rifle features an F-Class, single-shot Surgeon action with a Bartlein 5R barrel chambered with a no-turn neck. Gary says “The barrel only has 70 rounds through it… yep, I think it will shoot.” Gary did all of the gunsmithing and barrel work himself.
Did Gary have any special reloading tricks? Apparently not: “Other than weighing the cases and the powder very carefully, there really were no magical reloading secrets used. The Sierra 142s were moly-coated straight from the box of 500, but they were not weighed or checked for bearing surface. The powder was dropped with a RCBS ChargeMaster then checked with an Acculab scale (to under a tenth). The Lapua cases were not neck-turned, but I did weight-sort them. The five cases for the small group weighed: 195.05, 195.03, 195.03, 195.03, 195.01.”
Today, June 20, 2024 is Summer Solstice, the longest day of the year. And right now the Northeast USA is undergoing a major heatwave. That means “peak heat” summer conditions have arrived already. 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.
The way ambient temperatures, barrel heating, and powder warming can affect cartridge pressures (and hence velocities) was covered in a study Pressure Factors: How Temperature, Powder, and Primer Affect Pressure by Denton Bramwell. In that article, the author used 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.”
This Editor had the personal experience of 6mmBR hand-loaded ammo that was allowed to sit in the hot sun for 45 minutes while steel targets were reset. The brass became quite warm to the touch, meaning the casings were well over 120° on the outside. When I then shot this ammo, the bullets impacted well high at 600 yards (compared to earlier in the day). Using a Magnetospeed, I then chron-tested the sun-heated ammo. The hot ammo’s velocity FPS had increased very significantly — all because I had left the ammo out in the hot sun uncovered for 3/4 of an hour.
LESSON: Keep your ammo cool! Keep loaded ammo in the shade, preferably under cover or in an insulated container. You can use a SEALED cool pack inside the container, but we do NOT recommend H20 ice packs. And don’t have the container do double duty for food and beverages.
Powder Heat Sensitivity Comparison Test
Our friend Cal Zant of the Precision Rifle Blog has published a fascinating 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 Enduron line of propellants.
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. [NOTE: New Alliant Reloder TS 15.5 has also proved very temp stable in AccurateShooter’s range tests.]
Hodgdon Powder Company (Hodgdon) offers a series of professionally-produced, “how-to” instructional videos on its online Reloading Data Center. These 3.5-minute videos present rifle, pistol, and shotshell reloading basics in an easy-to-understand, step-by-step format. These mobile-friendly, informative videos can also be viewed on a smart phone or tablet.
Along with these videos, you’ll find a ton of useful information on Hodgdon’s updated Reloading Data Center at hodgdon.com. From the landing page choose rifle, pistol, shotgun, or muzzle-loader, and then click “Get Details”. This will launch a page where you can find loads by selecting Cartridge, Bullet Weight, Powder Maker, and Powder Type (such as Varget or H4350).
Click to Watch Hodgdon Rifle Reloading Video:
Click to Watch Hodgdon Pistol Reloading Video:
In addition to these videos, Hodgdon’s Reloading Data Center (RDC) provides a wealth of information on Hodgdon®, IMR®, Accurate, Ramshot®, and Winchester® propellants. Along with reliable load data, you’ll find explanations of reloading basics, safety procedures, plus answers to frequently asked questions (FAQ).
Hodgdon Reloading Data Center
Looking for a good load for a new rifle? Or perhaps you want to try a new powder and bullet combo for an existing rig. One of the best places to start for load data is Hodgdon’s online Reloading Data Center for pistol, rifle, and shotgun reloaders. Check out the Reloading Data Center at www.HodgdonReloading.com.
In the Data Center, you’ll find thousands of load recipes for pistol, rifle, and shotgun. Rifle shooters will find dozens of loads for their favorite Hodgdon, IMR, Accurate, Ramshot, and Winchester powders.
Benchrest, F-Class, Silhouette, ELR, and PRS/NRL competitors will find ultra-accurate loads for H4198, H4895, Varget, H4350, H4831sc, IMR 8208 XBR and other popular propellants. Hodgdon’s Reloading Center is “mobile-friendly” so it works well with smartphones and tables. Navigation is easy, and you can set the search criteria easily choosing your favorite powder or bullets. After choosing a cartridge, you can pre-select specific bullet weights and powder types. That quickly delivers just the information you want and need. You won’t have to scroll through scores of entries for bullets or powders you don’t use.
NOTE: This shows results for two bullet weights and two powder choices. With more powders and bullets selected you will get more results. The “BUY NOW” buttons link to the Hodgdon webstore.
Reloading Center is Smartphone-Friendly
Mobile users will notice that the current Hodgdon Reloading Center is “user-friendly” for smart-phone and tablet users. Controls have been optimized for touch-screens, and buttons are large and easy to use.
How to Get Started with Handloading
Getting started in Reloading? Ultimate Reloader offers a helpful introductory video that covers the basics. In addition, a recent Ultimate Reloader article reviews the types of reloading presses, plus the other gear you’ll need, from dies to powder dispensers.
The Summer Solstice is June 21, 2023, just a week away. And July is coming very soon. That means “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.
To 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.”
This Editor had the personal experience of 6mmBR hand-loaded ammo that was allowed to sit in the hot sun for 45 minutes while steel targets were reset. The brass became quite warm to the touch, meaning the casings were well over 120° on the outside. When I then shot this ammo, the bullets impacted well high at 600 yards (compared to earlier in the day). Using a Magnetospeed, I then chron-tested the sun-heated ammo. The hot ammo’s velocity FPS had increased very significantly — all because I had left the ammo out in the hot sun uncovered for 3/4 of an hour.
LESSON: Keep your ammo cool! Keep loaded ammo in the shade, preferably under cover or in an insulated container. You can use a SEALED cool pack inside the container, but we do NOT recommend H20 ice packs. And don’t have the container do double duty for food and beverages.
Powder Heat Sensitivity Comparison Test
Our friend Cal Zant of the Precision Rifle Blog has published a fascinating 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 Enduron line of propellants.
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. [NOTE: New Alliant Reloder TS 15.5 has also proved very temp stable in AccurateShooter’s range tests.]
Looking for a good load for a new rifle? Or perhaps you want to try a new powder and bullet combo for an existing rig. One of the best places to start for load data is Hodgdon’s online Reloading Data Center for pistol, rifle, and shotgun reloaders. Check out the Reloading Data Center at www.HodgdonReloading.com.
In the Data Center, you’ll find thousands of load recipes for pistol, rifle, and shotgun. Rifle shooters will find dozens of loads for their favorite Hodgdon, IMR, and Winchester powders such as H4198, H4895, Varget, H4350, and IMR 8208 XBR. And Hodgdon’s Reloading Center is “mobile-friendly” so it works well with smartphones and tables. Navigation is easy, and you can set the search criteria easily choosing your favorite powder or bullets. After choosing a cartridge, you can pre-select specific bullet weights and powder types. That quickly delivers just the information you want and need. You won’t have to scroll through scores of entries for bullets or powders you don’t use.
NOTE: This shows results for two bullet weights and two powder choices. With more powders and bullets selected you will get more results. The “BUY NOW” buttons link to the Hodgdon webstore.
Reloading Center is Smartphone-Friendly
Mobile users will notice that the current Hodgdon Reloading Center is “user-friendly” for smart-phone and tablet users. Controls have been optimized for touch-screens, and buttons are large and easy to use.
How to Get Started with Handloading
Getting started in Reloading? Ultimate Reloader offers a helpful introductory video that covers the basics. In addition, a recent Ultimate Reloader article reviews the types of reloading presses, plus the other gear you’ll need, from dies to powder dispensers.
Today, June 21, 2022, is Summer Solstice! This means today has the longest period of daylight of any day of the year. And July is right around the corner. That means “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.
To 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.”
This Editor had the personal experience of 6mmBR hand-loaded ammo that was allowed to sit in the hot sun for 45 minutes while steel targets were reset. The brass became quite warm to the touch, meaning the casings were well over 120° on the outside. When I then shot this ammo, the bullets impacted well high at 600 yards (compared to earlier in the day). Using a Magnetospeed, I then chron-tested the sun-heated ammo. The hot ammo’s velocity FPS had increased very significantly — all because I had left the ammo out in the hot sun uncovered for 3/4 of an hour.
LESSON: Keep your ammo cool! Keep loaded ammo in the shade, preferably under cover or in an insulated container. You can use a SEALED cool pack inside the container, but we do NOT recommend H20 ice packs. And don’t have the container do double duty for food and beverages.
Powder Heat Sensitivity Comparison Test
Our friend Cal Zant of the Precision Rifle Blog has published a fascinating 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 Enduron line of propellants.
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. [NOTE: New Alliant Reloder TS 15.5 has also proved very temp stable in AccurateShooter’s range tests.]
What’s a “wallet group”? It’s a singularly spectacular proof target that entitles its bearer to bragging rights. The wallet group may or may not have been shot in competition, and, by definition, it may not be repeatable. But it exists as incontrovertible proof that, at least once, the stars aligned, and the wind gods smiled on the shooter.
Five Shots in 0.178 MOA at 1000 Yards
A few years ago, Forum member and F-Class shooter Gary Wood was testing his 6.5-284 rifle at the 1000-yard range in Coalinga, California, getting ready for an upcoming long range match. In practice, Gary nailed a witnessed 1.859″ five-shot group, with four of the five shots well under an inch. Use this as proof to win those club-house arguments about whether it is possible to shoot “in the ones” at 1000 yards. Gary’s group worked out to 0.178 MOA!
Gary reports: “I was load testing with 5-shot groups. Each group was shot on a new F-Class center and pulled by Ret. Master Chief Jerry Pullens and spotted by an other long-range shooter. The second 5-shot load group looked really small … by our reckoning four out of five shots measured under an inch. I was amazed. What’s more, when I shot the group, the 4th shot blew the spindle out of the 3rd shot. My spotter saw that in his scope and Jerry Pullens told me about it afterwards”.
As measured with the OnTarget Software, using a scan of the target, Gary plotted the group size at 1.859″ total for five shots, or 0.178 MOA. Gary noted: “I had everyone sign the target which I saved and photographed.” Yes, Gary, this may be the wallet group to end all wallet groups. You should have that target framed.
Gary’s Load and 6.5-284 Rifle Specs
Gary was running a stout load of Hodgdon H4350 and CCI BR-2 primers, pushing moly-coated 142gr Sierra MKs, in Lapua 6.5-284 brass. The rifle features an F-Class, single-shot Surgeon action with a Bartlein 5R barrel chambered with a no-turn neck. Gary says “The barrel only has 70 rounds through it… yep, I think it will shoot.” Gary did all of the gunsmithing and barrel work himself.
Did Gary have any special reloading tricks? Apparently not: “Other than weighing the cases and the powder very carefully, there really were no magical reloading secrets used. The Sierra 142s were moly-coated straight from the box of 500, but they were not weighed or checked for bearing surface. The powder was dropped with a RCBS ChargeMaster then checked with an Acculab scale (to under a tenth). The Lapua cases were not neck-turned, but I did weight-sort them. The five cases for the small group weighed: 195.05, 195.03, 195.03, 195.03, 195.01.”
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.
The way ambient temperatures, barrel heating, and powder warming can affect cartridge pressures (and hence velocities) was covered in a study Pressure Factors: How Temperature, Powder, and Primer Affect Pressure by Denton Bramwell. In that article, the author used a pressure trace instrument to analyze how temperature affects ammo performance. Bramwell’s tests yielded some fascinating results.
Five Shots in 0.178 MOA at 1000 Yards
To learn more about how ambient temperature (and primer choice) affect pressures (and hence velocities) you should read the article 
