Sierra Bullets has released extensive load data for the popular 6.5 Creedmoor cartridge. This medium-sized cartridge has become one of the most popular chamberings for tactical and PRS shooters. The 6.5 Creedmoor combines excellent accuracy, good mag-feeding, good barrel life, moderate recoil, and reasonable component cost. That’s why this cartridge has caught on quickly, and is now one of the most popular chamberings in factory rifles.
Developed in 2007 by Dennis DeMille and Dave Emary, the 6.5 Creedmoor is a shortened and improved 30 TC cartridge case that was inspired by the .308 Winchester design. This short action design was created to maximize case capacity and a wide range of loading lengths, while still fitting in standard short action magazines. With the correct twist barrel, the versatile 6.5 Creedmoor can take advantage of the wide range of bullet weights available in 6.5 mm (i.e. .264 caliber). Reloaders should keep in mind that the 6.5 Creedmoor works best with medium to medium-slow powders such as H4350, Varget, Win 760, and RE-17. The light recoil and adaptability of the efficient 6.5 Creedmoor cartridge has already proven itself in high power, precision rifle series and benchrest competitions. Couple that with respectable barrel life and its intrinsic accuracy potential and you have a recipe for success which should insure its legacy for decades to come.
Here are three tables from the Sierra Bullets Reloading Manual (5th Edition). IMPORTANT — This is just a sample!! Sierra has load data for many other 6.5mm bullet types, including FB, Spitzer, SBT, HPBT, and Tipped MK from 85 grains to 142 grains. To view ALL 6.5 Creedmoor DATA, CLICK HERE.
INDICATES MAXIMUM LOAD – USE CAUTION
LOADS LESS THAN MINIMUM CHARGES SHOWN ARE NOT RECOMMENDED.
INDICATES MAXIMUM LOAD – USE CAUTION
LOADS LESS THAN MINIMUM CHARGES SHOWN ARE NOT RECOMMENDED.
INDICATES MAXIMUM LOAD – USE CAUTION
LOADS LESS THAN MINIMUM CHARGES SHOWN ARE NOT RECOMMENDED.
Two More Great 6.5 Creedmoor Reloading Resources
Want More 6.5 Creedmoor Load Info? View Starline’s 6.5 Creedmoor Guide by Gavin Gear:
PRB 6mm Creedmoor and 6.5 Creedmoor Load Survey
The Precision Rifle Blog compiled Load Data from PRS Competitors, for both 6mm Creedmoor and 6.5 Creedmoor. This is a good place to start. PRB surveyed the match loads for “173 of the top-ranked precision rifle shooters in the country”. CLICK HERE.
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A while back, Cal Zant at PrecisionRifleBlog.com did a big muzzle brake comparison test. Along with measuring recoil reduction, Cal’s team recorded sound levels in PRB’s exhaustive muzzle brake field test. In the PRB archives you’ll find comprehensive muzzle brake sound test results, with hard data on 20 different muzzle brakes.
Sound can be a tricky subject, but Cal Zant, the editor of PrecisionRifleBlog.com, presents everything an informed shooter should know about muzzle brake noise in a straightforward and practical way. Most sound tests are measured from the side of the muzzle, in accordance with mil-spec standards, and Cal did that. But he also measured the sound level of each brake from behind the rifle, closer to the shooter’s position. This provides a more accurate indicator of the actual sound levels that firearms operators will encounter while shooting their rifles.
Muzzle brakes ARE really loud — that’s something most active shooters have observed. But this study finally gives us some hard data and makes objective comparisons. The difference between brakes was quite significant. Some brakes were ear-splitting — more than twice as loud as other brakes tested.
As a bonus, Cal also provides data on how the new Ultra series suppressors from Thunder Beast Arms Corp (TBAC) compare in terms of sound level behind the rifle.
A while back, the Precision Rifle Blog conducted a fascinating study of Muzzle Brakes. PRB figured out a way to show the actual “blast pattern” of gasses ejecting from the ports of muzzle brakes. The result was a fascinating (and eye-catching) series of images revealing the distinctive gas outflows of 20+ different types of muzzle brakes. If you are considering buying and installing a muzzle brake on your rifle, you should definitely review this important PRB Muzzle Brake Test.
For a prone shooter, particularly on dusty, dirty or sandy ground, muzzle blast is a major bummer. Muzzle blast can be very disturbing — not just for the trigger-puller but for persons on either side of the gun as well. Some muzzle brakes send a huge shockwave back towards the shooter, and others send blast towards the ground, kicking dirt and debris into the prone shooter’s face. If there was a way to illustrate those factors — shockwave and debris — that might help shooters select one brake design over another.
Cal Zant at PrecisionRifleBlog.com applied a unique blend of creativity and resourcefulness to try to answer that question for 20+ muzzle brakes. Using high-speed photography and household products, he captured the blast pattern of 20+ different brake designs for easy side-by-side comparison. Can you figure out how Cal managed to show muzzle brake blasts so clearly? His “hi-viz” solution, revealed in the article, is very clever. See the eye-opening results for 20+ brakes, with illustrative photos, by visiting the Precision Rifle Blog Muzzle Brake Ground Signature Test Page.
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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.]
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Sierra Bullets has released extensive load data for the popular 6.5 Creedmoor cartridge. This medium-sized cartridge has become one of the most popular chamberings for tactical and PRS shooters. The 6.5 Creedmoor combines excellent accuracy, good mag-feeding, good barrel life, moderate recoil, and reasonable component cost. That’s why this cartridge has caught on quickly, and is now one of the most popular chamberings in factory rifles.
Developed in 2007 by Dennis DeMille and Dave Emary, the 6.5 Creedmoor is a shortened and improved 30 TC cartridge case that was inspired by the .308 Winchester design. This short action design was created to maximize case capacity and a wide range of loading lengths, while still fitting in standard short action magazines. With the correct twist barrel, the versatile 6.5 Creedmoor can take advantage of the wide range of bullet weights available in 6.5 mm (i.e. .264 caliber). Reloaders should keep in mind that the 6.5 Creedmoor works best with medium to medium-slow powders such as H4350, Varget, Win 760, and RE-17. The light recoil and adaptability of the efficient 6.5 Creedmoor cartridge has already proven itself in high power, precision rifle series and benchrest competitions. Couple that with respectable barrel life and its intrinsic accuracy potential and you have a recipe for success which should insure its legacy for decades to come.
Here are three tables from the Sierra Bullets Reloading Manual (5th Edition). IMPORTANT — This is just a sample!! Sierra has load data for many other 6.5mm bullet types, including FB, Spitzer, SBT, HPBT, and Tipped MK from 85 grains to 142 grains. To view ALL 6.5 Creedmoor DATA, CLICK HERE.
INDICATES MAXIMUM LOAD – USE CAUTION
LOADS LESS THAN MINIMUM CHARGES SHOWN ARE NOT RECOMMENDED.
INDICATES MAXIMUM LOAD – USE CAUTION
LOADS LESS THAN MINIMUM CHARGES SHOWN ARE NOT RECOMMENDED.
INDICATES MAXIMUM LOAD – USE CAUTION
LOADS LESS THAN MINIMUM CHARGES SHOWN ARE NOT RECOMMENDED.
Two More Great 6.5 Creedmoor Reloading Resources
Want More 6.5 Creedmoor Load Info? View Starline’s 6.5 Creedmoor Guide by Gavin Gear:
PRB 6mm Creedmoor and 6.5 Creedmoor Load Survey
The Precision Rifle Blog compiled Load Data from PRS Competitors, for both 6mm Creedmoor and 6.5 Creedmoor. This is a good place to start. PRB surveyed the match loads for “173 of the top-ranked precision rifle shooters in the country”. CLICK HERE.
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A while back, the Precision Rifle Blog conducted a fascinating study of Muzzle Brakes. PRB figured out a way to show the actual “blast pattern” of gasses ejecting from the ports of muzzle brakes. The result was a fascinating (and eye-catching) series of images revealing the distinctive gas outflows of 20+ different types of muzzle brakes. If you are considering buying and installing a muzzle brake on your rifle, you should definitely review this important PRB Muzzle Brake Test.
For a prone shooter, particularly on dusty, dirty or sandy ground, muzzle blast is a major bummer. Muzzle blast can be very disturbing — not just for the trigger-puller but for persons on either side of the gun as well. Some muzzle brakes send a huge shockwave back towards the shooter, and others send blast towards the ground, kicking dirt and debris into the prone shooter’s face. If there was a way to illustrate those factors — shockwave and debris — that might help shooters select one brake design over another.
Cal Zant at PrecisionRifleBlog.com applied a unique blend of creativity and resourcefulness to try to answer that question for 20+ muzzle brakes. Using high-speed photography and household products, he captured the blast pattern of 20+ different brake designs for easy side-by-side comparison. Can you figure out how Cal managed to show muzzle brake blasts so clearly? His “hi-viz” solution, revealed in the article, is very clever. See the eye-opening results for 20+ brakes, with illustrative photos, by visiting the Precision Rifle Blog Muzzle Brake Ground Signature Test Page.
Share the post "See How Muzzle Brakes Really Work with Blast Trace Tests"
Sierra Bullets has released extensive load data for the popular 6.5 Creedmoor cartridge. This medium-sized cartridge has become one of the most popular chamberings for tactical and PRS shooters. The 6.5 Creedmoor combines excellent accuracy, good mag-feeding, good barrel life, moderate recoil, and reasonable component cost. That’s why this cartridge has caught on quickly, and is now one of the most popular chamberings in factory rifles.
Developed in 2007 by Dennis DeMille and Dave Emary, the 6.5 Creedmoor is a shortened and improved 30 TC cartridge case that was inspired by the .308 Winchester design. This short action design was created to maximize case capacity and a wide range of loading lengths, while still fitting in standard short action magazines. With the correct twist barrel, the versatile 6.5 Creedmoor can take advantage of the wide range of bullet weights available in 6.5 mm (i.e. .264 caliber). Reloaders should keep in mind that the 6.5 Creedmoor works best with medium to medium-slow powders such as H4350, Varget, Win 760, and RE-17. The light recoil and adaptability of the efficient 6.5 Creedmoor cartridge has already proven itself in high power, precision rifle series and benchrest competitions. Couple that with respectable barrel life and its intrinsic accuracy potential and you have a recipe for success which should insure its legacy for decades to come.
Here are three tables from the Sierra Bullets Reloading Manual (5th Edition). IMPORTANT — This is just a sample!! Sierra has load data for many other 6.5mm bullet types, including FB, Spitzer, SBT, HPBT, and Tipped MK from 85 grains to 142 grains. To view ALL 6.5 Creedmoor DATA, CLICK HERE.
INDICATES MAXIMUM LOAD – USE CAUTION
LOADS LESS THAN MINIMUM CHARGES SHOWN ARE NOT RECOMMENDED.
INDICATES MAXIMUM LOAD – USE CAUTION
LOADS LESS THAN MINIMUM CHARGES SHOWN ARE NOT RECOMMENDED.
INDICATES MAXIMUM LOAD – USE CAUTION
LOADS LESS THAN MINIMUM CHARGES SHOWN ARE NOT RECOMMENDED.
Two More Great 6.5 Creedmoor Reloading Resouces
Want More 6.5 Creedmoor Load Info? View Starline’s 6.5 Creedmoor Guide by Gavin Gear:
PRB 6mm Creedmoor and 6.5 Creedmoor Load Survey
The Precision Rifle Blog compiled Load Data from PRS Competitors, for both 6mm Creedmoor and 6.5 Creedmoor. This is a good place to start. PRB surveyed the match loads for “173 of the top-ranked precision rifle shooters in the country”. CLICK HERE.
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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.]
Share the post "Keep Your Cartridges Cool During Hot Summer Months"
A while back, Cal Zant at PrecisionRifleBlog.com did a big muzzle brake comparison test. Along with measuring recoil reduction, Cal’s team recorded sound levels in PRB’s exhaustive muzzle brake field test. In the PRB archives you’ll find comprehensive muzzle brake sound test results, with hard data on 20 different muzzle brakes.
Sound can be a tricky subject, but Cal Zant, the editor of PrecisionRifleBlog.com, presents everything an informed shooter should know about muzzle brake noise in a straightforward and practical way. Most sound tests are measured from the side of the muzzle, in accordance with mil-spec standards, and Cal did that. But he also measured the sound level of each brake from behind the rifle, closer to the shooter’s position. This provides a more accurate indicator of the actual sound levels firearms operators will encounter while shooting.
Muzzle brakes ARE really loud — that’s something most active shooters have observed. But this study finally gives us some hard data and makes objective comparisons. The difference between brakes was quite significant. Some brakes were ear-splitting — more than twice as loud as other brakes tested.
As a bonus, Cal also provides data on how the new Ultra series suppressors from Thunder Beast Arms Corp (TBAC) compare in terms of sound level behind the rifle.
Sierra Bullets has released very complete load data for the popular 6.5 Creedmoor cartridge. This medium-sized cartridge has become one of the most popular chamberings for tactical and PRS shooters. The 6.5 Creedmoor combines excellent accuracy, good mag-feeding, good barrel life, moderate recoil, and reasonable component cost. That’s why this cartridge has caught on quickly.
Developed in 2007 by Dennis DeMille and Dave Emary, the 6.5 Creedmoor is a shortened and improved 30 TC cartridge case that was inspired by the .308 Winchester design. This short action design was created to maximize case capacity and a wide range of loading lengths, while still fitting in standard short action magazines. With the correct twist barrel, the versatile 6.5 Creedmoor can take advantage of the wide range of bullet weights available in 6.5 mm (i.e. .264 caliber). Reloaders should keep in mind that the 6.5 Creedmoor works best with medium to medium-slow powders such as H4350, Varget, Win 760, and RE-17. The light recoil and adaptability of the efficient 6.5 Creedmoor cartridge has already proven itself in high power, precision rifle series and benchrest competitions. Couple that with respectable barrel life and its intrinsic accuracy potential and you have a recipe for success which should insure its legacy for decades to come.
Here are three tables from the Sierra Bullets Reloading Manual (5th Edition). IMPORTANT — This is just a sample!! Sierra has load data for many other 6.5mm bullet types, including FB, Spitzer, SBT, HPBT, and Tipped MK from 85 grains to 142 grains. To view ALL 6.5 Creedmoor DATA, CLICK HERE.
INDICATES MAXIMUM LOAD – USE CAUTION
LOADS LESS THAN MINIMUM CHARGES SHOWN ARE NOT RECOMMENDED.
INDICATES MAXIMUM LOAD – USE CAUTION
LOADS LESS THAN MINIMUM CHARGES SHOWN ARE NOT RECOMMENDED.
INDICATES MAXIMUM LOAD – USE CAUTION
LOADS LESS THAN MINIMUM CHARGES SHOWN ARE NOT RECOMMENDED.
Two More Great 6.5 Creedmoor Reloading Resouces
Want More 6.5 Creedmoor Load Info? View Starline’s 6.5 Creedmoor Guide by Gavin Gear:
PRB 6mm Creedmoor and 6.5 Creedmoor Load Survey
The Precision Rifle Blog compiled Load Data from PRS Competitors, for both 6mm Creedmoor and 6.5 Creedmoor. This is a good place to start. PRB surveyed the match loads for “173 of the top-ranked precision rifle shooters in the country”. CLICK HERE.
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Many of our readers are thinking of trying out PRS-type competition. Tactical matches are becoming more popular every season. Along with F-Class, tactical/practical disciplines are the fastest-growing forms of competitive rifle shooting. Rich Emmons, one of the founders of the Precision Rifle Series (PRS), has written an insightful article about getting started in the tactical game. This will help PRS novices pick the right equipment and understand the game. Here are highlights from Emmon’s “PRS — Intro to Competition” article, originally published on the PRS website. You may also want to read the current PRS FAQ Page.
Precision Rifle Series — Intro to Competition
by Rich Emmons, PRS President
Tactical Shooting with a precision rifle is not like other disciplines, there is no set course of fire or format. That is what makes it so fun!
First, you have to ask yourself what do you want to accomplish. When I was introduced to long range shooting, immediately a light turned on for me, once I saw how easy it was to hit 300–600 yard targets. What I quickly learned from my first competition and the many that followed was there is so much to learn and shooting in competition put everything you thought you knew to the test. So back to the question: “What do YOU want to accomplish?”. The reality is you may not know yet, you just think it is cool to have a bad ass rifle and scope that can make almost any shot. Now if you’ve got that rifle and scope, it’s time to take it to the next level.
Watch PRS 2016 Championship
Getting Started — What to Expect
If you’re reading this, you have probably already have been bitten by the long range shooting bug. It can seem quite intimidating to just jump in with a new bunch of shooters you don’t know and shooting lingo you don’t quite understand yet. But here is the key — show up and shoot! I guarantee you if you show up to a match as a new shooter, other experienced shooters will guide you along and give you help on anything you need.
AUDIO: Click Button to hear Rich Emmons Talk about the Precision Rifle Series.
Now, a couple things you should just expect. You’re not as good as you think you are. Don’t expect to come into your first match and beat all the veterans. That just doesn’t happen unless you have had some really good coaching or other shooting competition experience to get you ready for this type of competition. If possible, find a local rifle club that has monthly long range matches, or any type of match will help prepare you for a larger PRS event. Getting involved with a rifle club and starting out shooting monthly matches is definitely the way to jump into competition shooting.
The Gear You Need
The first question that many ask is: “What kind of rifle/caliber/scope do I need?” The easiest answer to this is, the best you can afford. It’s no secret the gear is expensive. It took me several years of buying sub-par gear and eventually trading up to figure this out. Now, a guy can get a real sense of pride of doing it on the cheap, or with a factory rifle. I’ve seen many old Savage 10FPs take down custom rigs that cost 10 times as much. And if that’s all you can afford, then eventually you will learn the limitations of yourself or your gear. As for choice of cartridge/caliber, the respected Precision Rifle Blog has analyzed five years worth of match results from the best tactical shooters in the nation. CLICK HERE to read a PRB article that reveals what cartridge types the “top guns” use.
Craig Arnzen of Area 419 has created a useful article reviewing the gear PRS shooters need, including support bags, hearing protection, and other key accessories such as muzzle brakes. This helpful article also covers factory ammunition options.
Making Good Ammo
Producing quality reloads is something you have to master. It’s not hard at all, you just have to pay attention to detail, and eventually you are going to do something stupid like mis-priming your brass, or skip a row of brass when dumping your powder. Everybody has their own horror story of some reloading failure that cost them a stage or even a match. So load to perfection, work with your rifle to find what load it likes the best, then start your practice.
Practice Makes Perfect
You want to become ONE with your rifle, learning everything you can about its functionality. Getting comfortable with the operation of your rifle is key. Learn the feel of your trigger, dry-firing until you wear the paint off your bolt handle. Learn how the rifle works best — pay attention to little things like the sound and feel of the bolt feeding a round from the mag (or when it doesn’t). Learn how to remove a jammed round quickly, learn how to reload a magazine quickly. Learn to scan across a field and find targets in a quick manner, seeing the targets with your eye and coming into the scope on target. These are some of the basic practices that separate the new shooters from the seasoned ones.
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Summer Solstice 2020 was June 20th, and July’s nearly here. 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.
Powder Heat Sensitivity Comparison Test
Our friend Cal Zant of the Precision Rifle Blog recently 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.
Share the post "Don’t Overheat Your Ammo in Hot Summer Months"
Developed in 2007 by Dennis DeMille and Dave Emary, the 6.5 Creedmoor is a shortened and improved 30 TC cartridge case that was inspired by the .308 Winchester design. This short action design was created to maximize case capacity and a wide range of loading lengths, while still fitting in standard short action magazines. With the correct twist barrel, the versatile 6.5 Creedmoor can take advantage of the wide range of bullet weights available in 6.5 mm (i.e. .264 caliber). Reloaders should keep in mind that the 6.5 Creedmoor works best with medium to medium-slow powders such as H4350, Varget, Win 760, and RE-17. The light recoil and adaptability of the efficient 6.5 Creedmoor cartridge has already proven itself in high power, precision rifle series and benchrest competitions. Couple that with respectable barrel life and its intrinsic accuracy potential and you have a recipe for success which should insure its legacy for decades to come.
To learn more about how ambient temperature (and primer choice) affect pressures (and hence velocities) you should read the article 
To learn more about how ambient temperature (and primer choice) affect pressures (and hence velocities) you should read the article 
