August 1st, 2007

Effects of Heat on Powder Performance

Hodgdon has produced some interesting tables that show how changing temperatures affect the performance of various powders. While most powders generate higher velocities as temperatures rise, it is interesting to note that some powders experience much smaller velocity shifts than others. Here are two charts prepared by Hodgdon:

Extreme Velocity Spread For Temps Between 0°-125°

Cartridge: 30-06
Case: W-W
Primer: WLR
165 gr. Hornady SP

Cartridge: 300 Win. Mag.
Case: W-W
Primer: WLRM
180 gr. Sierra Boat Tail SP

To learn more about how ambient temperature (and primer choice) affect pressures (and hence velocities) you should read the article “Pressure Factors” by Denton Bramwell. In that article, the author uses a pressure trace instrument to analyze how temperature affects powder 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 degree 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.

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August 1st, 2007

Ramshot Hunter Powder $9.99/lb

Ramshot hunter powderMidwayUSA now has Ramshot Hunter on sale for $9.99 per pound, item # 920960. That’s $5.50 off the regular price of $15.49 per pound. Ramshot Hunter is a quality ball powder that meters easily, with a burn rate similar to H4350, Norma 204, or Alliant Reloader 19. It is a good choice for the 22-250, 6-6.5×47, 6XC, and the short magnum cartridges. Ramshot Hunter’s small spherical particles pack tightly, offering good velocities in cases that are short on capacity. If you’ve run out of room with H4350, consider Ramshot Hunter. The sale ends August 31, 2007.

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August 1st, 2007

Joe Krupa Earns HOF Entry

James Mock reports that Joe Krupa shot his way into the Benchrest Hall of Fame at the IBS Nationals now underway in St. Louis: “Joe used his great shooting Jay Young rail gun to win three more Hall of Fame points. These three points gave him 11 total. That means that he is our newest member of the BR Hall of Fame. Congratulations Joe.” Joe’s Agg for the Unlimited Class 200-yard Heavy Bench gun was .2866, while his Grand Agg was .2934″. For more information, read this thread on Benchrest.com.

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