temperature to velocity variation input

[scott]

Anyone have any info on temperature variation with different powders..

Example, a 243, 6mm, 257, 25-06, 270,7mm 30-06, 300's etc using Re-19-22-25 or IMR-4831 4350 etc
from a cold 20-25 deg day (what vel do you get?), on up to 60-70 deg (what vel do you get now).

I have not done enough testing myself to make anything yet, I'd like to know how ball powders compare to stick powders from 20-70 deg or something around that. have any of you have done any temperature to velocity testing?

scott

 

[royinidaho]

58.9gr RL-22 270Win 27" bbl = 3200 FPS on 70/80 degree summer day. When in 90s, don't shoot that load.

Same load in fall/winter @ about freezing is 130 FPS less.

 

[davewilson]

i think most concentrate on how much extra powder they need to get the same velocity when it's cold rather than how much slower it is.

 

[royinidaho]

[ QUOTE ]
i think most concentrate on how much extra powder they need to get the same velocity when it's cold rather than how much slower it is.

[/ QUOTE ]

Dave,

I do that also. This was an unintended discovery. I 'just happened' to shoot over the chrono on a very cool day for no good reason at all. I was suprised that the velocity difference was that large. Still shot good though. But needed a new drop chart for cool weather shooting. I'm not trustworthy enough to keep a load for each season. /ubbthreads/images/graemlins/frown.gif

 

[brianwinzor]

Scott, I have numerous examples of temperature variation that I could use, but here is one example and I will look up records for others.
Example 1
25/06 AI Rem Case, Fed 215 Primer, Nosler 100 grn SPBT LL 3.180 Load 60.5 grains IMR 4831

01/06/1988 - Temp 11C (52F) - 3,554 FPS (3 shot group)
01/07/1988 - Temp 15C (59F) - 3,589 FPS (3 shot group)
20/03/1989 - Temp 28C (83F) - 3,673 FPS (15 shots 3 groups)
19/05/1990 - Temp 14C (57F) - 3,547 FPS (3 shot group)

My experience is that all powders that I have tested seem to increase in velocity as temperature increases. Although some may rise more than others. Regards, Brian

 

[davewilson]

Brian,not on subject but why are you using a 215 primer with that case? i'll bet you'd get a better ES and downrange accuracy with a milder primer.

 

[brianwinzor]

Dave, That test was done 18 years ago, when my gunsmith recommended me to use magnum primers. I still use magnum primers whenever I am using ball powders, and especially when I am using H870. However, I have been using the Rem 91/2M primer recently and that does seem to be milder than the Fed 215.

I will take up your suggestion and do a test of a standard V magnum primers in my 25/06AI, and see what the results are. Regards, Brian.

 

[scott]

Thank you Roy.. That is one result I was looking for, 130 fps dif from 30 to 75 deg..

I would now like to know what ball powders will do under the same loadings or a simular round.

are we talking 200 to 300 fps or maybe up to 500 fps differance with ball powders or what?

thanks

scott