I have been using 2520 for many months now in my 22-250. I shoot 8 5 shot groups a week. Through the spring and summer I have been shooting an average of these 5 shot groups as low as .31 and a high of .48. The weather here in northeast PA has dropped. Once the temps dropped below 50 degrees the groups started to open up to an average of .53. Any thoughts on this from the experts out there?
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Is Accurate 2520 Temperature Sensitive
- Thread starter Poconolg
- Start date
Here is a quote from the Accurate Powders website:
http://www.accuratepowder.com/faq/
"
Most of our powders are not insensitive, and will show some effect at hot and cold temperatures.
However, we test at -40F and +125F and the deviation in most cases are ca 3% to 5% at these extreme levels. Therefore most shooters do not notice much difference under normal practical hunting conditions.
More elaboration on the subject:
Complete temperature stability can only be achieved with tubular extruded powders designs, either with double base (NG) and/or with other coating technologies.
Because the ballistic performance at extreme temperature is completely dependant on the specific combination, it is very difficult to quantify and qualify.
Our standard powders perform very well at extreme temperatures, and usually pass the strict military requirements by a large margin.
This is a subject that often fraught with misconceptions and inaccuracies.
The term is used loosely by manufacturers without qualifying the subject, and is obviously exploited for marketing purposes and perceptions.
The facts are:
Although powders can be improved, it’s really only possible with advanced coating procedures and additives which increase the cost.
A particular powder can be improved re temperature stability for certain combinations, within a certain envelope which is specific to the following three main parameters/aspects
The caliber.
The weight of the projectile/bullet.
The performance level.
If any of these parameters/aspects go beyond or outside the intended ratio/s, the results will change and the performance will sometimes be different.
It is also very important that when a comparison is made, that all conditions re weapon i.e. components primer, case, bullet and the velocity are equal, and preferably done at the same time on the same day."
http://www.accuratepowder.com/faq/
"
Most of our powders are not insensitive, and will show some effect at hot and cold temperatures.
However, we test at -40F and +125F and the deviation in most cases are ca 3% to 5% at these extreme levels. Therefore most shooters do not notice much difference under normal practical hunting conditions.
More elaboration on the subject:
Complete temperature stability can only be achieved with tubular extruded powders designs, either with double base (NG) and/or with other coating technologies.
Because the ballistic performance at extreme temperature is completely dependant on the specific combination, it is very difficult to quantify and qualify.
Our standard powders perform very well at extreme temperatures, and usually pass the strict military requirements by a large margin.
This is a subject that often fraught with misconceptions and inaccuracies.
The term is used loosely by manufacturers without qualifying the subject, and is obviously exploited for marketing purposes and perceptions.
The facts are:
Although powders can be improved, it’s really only possible with advanced coating procedures and additives which increase the cost.
A particular powder can be improved re temperature stability for certain combinations, within a certain envelope which is specific to the following three main parameters/aspects
The caliber.
The weight of the projectile/bullet.
The performance level.
If any of these parameters/aspects go beyond or outside the intended ratio/s, the results will change and the performance will sometimes be different.
It is also very important that when a comparison is made, that all conditions re weapon i.e. components primer, case, bullet and the velocity are equal, and preferably done at the same time on the same day."
I have had loads shoot great at some pretty cold temperature (down around zero ) and then not shoot at higher temps
And vice versa.
Keep in mind that high temps for us is 75 degrees.
For what its worth, a lot of people from hot places say our 75 is worse than theirs. Sun is more direct, less atmosphere and the summer angles.
I have not been able to explore all that but working back and forth on velocity.
I have shifted to the H (and one IMR) powder that is less temperature sensitive.
Good results in the one gun.
Its such a fun challenge, get a load going good and have it quit.
I don't see Accurate powders much if any lower than the others and I buy in 8 lb jugs now (never to be hit by a powder shortage again!). That drops the price per pound down 2 or 3 bucks.
And vice versa.
Keep in mind that high temps for us is 75 degrees.
For what its worth, a lot of people from hot places say our 75 is worse than theirs. Sun is more direct, less atmosphere and the summer angles.
I have not been able to explore all that but working back and forth on velocity.
I have shifted to the H (and one IMR) powder that is less temperature sensitive.
Good results in the one gun.
Its such a fun challenge, get a load going good and have it quit.
I don't see Accurate powders much if any lower than the others and I buy in 8 lb jugs now (never to be hit by a powder shortage again!). That drops the price per pound down 2 or 3 bucks.
reynolds357
New member
All powder is temperature sensitive. How much, is the question.
"A particular powder can be improved re temperature stability for certain combinations, within a certain envelope which is specific to the following three main parameters/aspects"
^^^This is the thing. Many people have noticed before that Varget does well with temperature insensitivity in .308 match loads (165-180 grain bullet weight range). When folks try the same tests (keep some rounds in cold packs vs keeping them under your armpit immediately before firing) with the .223, it doesn't seem to be any better on temperature than a number of other stick powders.
Poconolg,
I am wondering if you have a load on the edge of a sweet spot. Try upping the charge a half a grain. That's what QuickLOAD thinks would compensate for barrel time change going from 70° to 45° with a 34 grain load behind the 53 grain Hornady match bullet.
^^^This is the thing. Many people have noticed before that Varget does well with temperature insensitivity in .308 match loads (165-180 grain bullet weight range). When folks try the same tests (keep some rounds in cold packs vs keeping them under your armpit immediately before firing) with the .223, it doesn't seem to be any better on temperature than a number of other stick powders.
Poconolg,
I am wondering if you have a load on the edge of a sweet spot. Try upping the charge a half a grain. That's what QuickLOAD thinks would compensate for barrel time change going from 70° to 45° with a 34 grain load behind the 53 grain Hornady match bullet.