Barnes Bullets did a test with some interesting results....
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http://www.barnesbullets.com/resources/newsletters/july-2010-barnes-bullet-n/
Greggory Sloan
Special Projects/Ballistics Lab
Recently, Barnes’ Ballistics Lab performed a test using an environmental chamber to test the effects temperature has on handloads. This was a two part test. First, four different cartridges were loaded with an assortment of popular powders to see how extreme temperature, both hot and cold, would affect the consistency and stability of the powder. The second part of the test consisted of determining how extreme cold temperatures would have an effect on primers, specifically, testing the different affects between standard and magnum primers. In the interest of time, all of the rounds for each separate test were placed in the chamber and kept at temperature for two hours and then removed and fired immediately. These results could vary if loaded rounds were kept in the chamber for a longer period of time.
The following charts show that there were significant differences between the powders tested. From hot to cold temperatures, some powders were found to be very consistent, while others had velocity differences up to 250 ft/s and pressure differences up to 17,100 PSI. Keep in mind that these are extreme differences in temperature. These results don’t necessarily mean that if one powder is currently being used that didn’t perform well in the test, that it should not be used altogether. There are a lot of great powders that are used in the Barnes lab and for many of the lab technician’s personal handloading that produce excellent accuracy and consistency but did not produce good results in the test. One lesson learned is that when a load is worked up in 70 degree weather and then taken to the heat of Africa or the cold temperatures of Alaska, the velocity and pressure will most likely be different, which will most likely change the point of impact. This goes to show that a rifle’s zero should always be verified upon arrival at camp before the hunt. As long as it is understood that loads will perform differently in varying climates, it’s not essential to use a powder that proved a minimal difference in the test. However, the test also proved that there are some very stable and consistent powders available which can help eliminate variables associated with climate change in handloads. Figure 1 shows Alliant’s RL-10X did well in the .223 Rem and Figure 3 shows Hodgdon’s Varget also performed very well in the .308 Win. The .308 Win and Varget combination showed the velocity spread between the -40 degrees and the 120 degrees was only 29 ft/s! The 300 Win Mag loaded with Hodgdon’s H1000 and Ramshot’s Magnum also produced good results.
For the second part of the test, standard versus magnum primers were tested in cold weather to determine the differences, if any at all. It has been said that if a standard cartridge is being used, such as a .30-06, in cold weather, you should use a magnum primer. It has also been suggested that if a ball-type powder is being used, or if the cartridge is loaded with a larger charge (over 60 grains), that a magnum primer can be used. To research this, Barnes ballistics lab technicians tested one standard cartridge (.30-06) and one magnum cartridge (300 Win Mag) and used both primer types in each. Powders that gave consistent velocities and pressure readings, in both extruded and ball-type, were used. Just as the Figure 7 photo of frozen rounds shows, this was an extreme-conditions test. Throughout the test there were no issues with hang fires or misfires with either the standard or magnum primers. Figure 5 shows that the 300 Win Mag had no problems using a standard primer even with a full charge of Ramshot’s Magnum powder (ball-type). Velocities and pressures were slightly higher in the 300 Win Mag with standard primers over the magnum primers. The velocity standard deviation seemed to be more consistent from one temperature to another with the standard primers. The .30-06 test showed that pressure and velocity went down with a standard primer and using Hodgdon’s IMR 4064 powder, but was slightly higher with Hodgdon’s H414.
In conclusion, the results establish that changing to a magnum primer in a standard cartridge is unnecessary, even in cold temperatures. The test also shows that if standard primers are the only primers available, they can be used in belted magnum cases such as the 7mm Rem Mag, 300 Win Mag, etc…They would also work fine in the WSM family of cartridges.
Ultimately, the best rule of thumb is to simply follow the reloading manual’s recommendation for whichever load/cartridge combination you are using.
Scroll halfway down the page.
http://www.barnesbullets.com/resources/newsletters/july-2010-barnes-bullet-n/
Greggory Sloan
Special Projects/Ballistics Lab
Recently, Barnes’ Ballistics Lab performed a test using an environmental chamber to test the effects temperature has on handloads. This was a two part test. First, four different cartridges were loaded with an assortment of popular powders to see how extreme temperature, both hot and cold, would affect the consistency and stability of the powder. The second part of the test consisted of determining how extreme cold temperatures would have an effect on primers, specifically, testing the different affects between standard and magnum primers. In the interest of time, all of the rounds for each separate test were placed in the chamber and kept at temperature for two hours and then removed and fired immediately. These results could vary if loaded rounds were kept in the chamber for a longer period of time.
The following charts show that there were significant differences between the powders tested. From hot to cold temperatures, some powders were found to be very consistent, while others had velocity differences up to 250 ft/s and pressure differences up to 17,100 PSI. Keep in mind that these are extreme differences in temperature. These results don’t necessarily mean that if one powder is currently being used that didn’t perform well in the test, that it should not be used altogether. There are a lot of great powders that are used in the Barnes lab and for many of the lab technician’s personal handloading that produce excellent accuracy and consistency but did not produce good results in the test. One lesson learned is that when a load is worked up in 70 degree weather and then taken to the heat of Africa or the cold temperatures of Alaska, the velocity and pressure will most likely be different, which will most likely change the point of impact. This goes to show that a rifle’s zero should always be verified upon arrival at camp before the hunt. As long as it is understood that loads will perform differently in varying climates, it’s not essential to use a powder that proved a minimal difference in the test. However, the test also proved that there are some very stable and consistent powders available which can help eliminate variables associated with climate change in handloads. Figure 1 shows Alliant’s RL-10X did well in the .223 Rem and Figure 3 shows Hodgdon’s Varget also performed very well in the .308 Win. The .308 Win and Varget combination showed the velocity spread between the -40 degrees and the 120 degrees was only 29 ft/s! The 300 Win Mag loaded with Hodgdon’s H1000 and Ramshot’s Magnum also produced good results.
For the second part of the test, standard versus magnum primers were tested in cold weather to determine the differences, if any at all. It has been said that if a standard cartridge is being used, such as a .30-06, in cold weather, you should use a magnum primer. It has also been suggested that if a ball-type powder is being used, or if the cartridge is loaded with a larger charge (over 60 grains), that a magnum primer can be used. To research this, Barnes ballistics lab technicians tested one standard cartridge (.30-06) and one magnum cartridge (300 Win Mag) and used both primer types in each. Powders that gave consistent velocities and pressure readings, in both extruded and ball-type, were used. Just as the Figure 7 photo of frozen rounds shows, this was an extreme-conditions test. Throughout the test there were no issues with hang fires or misfires with either the standard or magnum primers. Figure 5 shows that the 300 Win Mag had no problems using a standard primer even with a full charge of Ramshot’s Magnum powder (ball-type). Velocities and pressures were slightly higher in the 300 Win Mag with standard primers over the magnum primers. The velocity standard deviation seemed to be more consistent from one temperature to another with the standard primers. The .30-06 test showed that pressure and velocity went down with a standard primer and using Hodgdon’s IMR 4064 powder, but was slightly higher with Hodgdon’s H414.
In conclusion, the results establish that changing to a magnum primer in a standard cartridge is unnecessary, even in cold temperatures. The test also shows that if standard primers are the only primers available, they can be used in belted magnum cases such as the 7mm Rem Mag, 300 Win Mag, etc…They would also work fine in the WSM family of cartridges.
Ultimately, the best rule of thumb is to simply follow the reloading manual’s recommendation for whichever load/cartridge combination you are using.
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