Spike Camp

An interesting article on temperaure sensitive vs not as sensitive powder

.257

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I agree temperature has an effect on your loads. Outside temps and chamber temps. Chamber temps has nothing to do with hunting but when at the range it does. Chambering a round and letting it set there for a minute will raise the pressure of that round in a hot barrel.
Mike

danno50

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I posed the temperature sensitive powder question and the recoil question to the Hornady Technical Assistance Team and got this response.
Dan,
Not speaking for Weatherby however, Hornady, like most major manufacturers, use commercial grade powders that are quite consistent and relatively resistant to temperature change but  are not actually Hodgdon  “temperature stable powders”.   You always want to enlist good ammunition handling procedures by not leaving ammunition exposed to direct elements especially the direct sun and heat, protecting it from these elements, as much as reasonably possible.
 
Superformance is a blended powder that starts with the over the counter Superformance powder and we add other commercial grade powders and components to it to get the specific blend we need based upon capacity, bullet weight and bore diameter, in part.    This powder, generally, does not produce more recoil but the perception there of, due to the different report, which is more of a boom than a bang.   This powder obtains higher velocity due to the fact it produces a greater volume of gas giving the bullet a constant push the entire length of the barrel within sub-SAAMI pressure standards.  We have over 30 different blends for the line of Superformance ammunition.
 
Thanks,
TZ
 
From: Hornady Manufacturing, Inc [mailto:webmaster@hornady.com]
Sent: Tuesday, May 17, 9:25 AM 2017
« Last Edit: May 17, 2017, 08:50:30 AM by danno50 »
DosEquisShooter

Very interesting Dan. Thanks for the post.
Roger
Faster horses,younger women,older whiskey,and more money.

.257

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Dan, that's is a interesting answer. The Superformance for sure, that is different than everything I have ever read about modern powder. I have a load with it in my 338 win mag with 185gr TTSX, very light recoil and very accurate, with good velocities
Mike

eford

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It's been a few years but I remember seeing a chart with the Superformance pressure curve. SF still ads at it peak pressure a weeee bit longer than the other powder (that might have been H 4350), therefore producing more velocity.
The ordinary Superformance, over the counter stuff is very good in my 280 Remington and 6.5mm Creedmoor. I wildcatted a load in my 257 Weatherby and it had stunning accuracy at 100 yards.
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.257

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It's been a few years but I remember seeing a chart with the Superformance pressure curve. SF still ads at it peak pressure a weeee bit longer than the other powder (that might have been H 4350), therefore producing more velocity.
The ordinary Superformance, over the counter stuff is very good in my 280 Remington and 6.5mm Creedmoor. I wildcatted a load in my 257 Weatherby and it had stunning accuracy at 100 yards.

I did the same thing in my .257. Like you accuracy was stunning, next put 5 shots thru the chronograph, it had a 130 fps  spread. I stopped there, the group wouldn't hold up at any distance
Mike

As a side note, I was playing around with one of the online ballistic calculators and generated a hypothetical temperature/trajectory  table using one of my pet 6.5 CM loads with IMR4350 and Nosler RDF 140's in my Vanguard. I started with 45 degrees and went up in 5 degree increments to 95 degrees with standard pressure at an elevation of 92 feet (elevation at my range). There was no difference in the hypothetical trajectory (dial-ups) from 45 to 95 degrees out to 500 yards. I tested it yesterday afternoon at 400 and 600 yards. The temp was 80 so I dialed up 1.8 mils and hit dead on. I then dialed up 4.0 mils and did the same at 600. What I consider dead on is a 1 MOA or less group. I plan to test it again early one morning at a lower temperature and see what happens. This is completely independent of powder temperature, although I assume it would be close to ambient since it was in the shade. Not all that scientific but I'm always doing stuff like this for fun and its a great excuse to burn some powder. And I always learn something.  I may generate some more tables and use temperature as a constant and pressure and humdity as variables to see what variable has the greatest impact on trajectory. I can't imagine that BP and humdity are "significant" when compared to temperature.

I did note that at 1,000 yards and at 45 degrees the dial-up was estimated at 10.2 mils. At 95 degrees the dial-up was 9.6 mils. A difference of 0.6 mils. 
« Last Edit: May 18, 2017, 09:09:30 AM by Downeast »