Magpro and temp sensitivity


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slabuda
July 19, 2013, 11:21 PM
I know temp sensitvity has been tossed around a lot. I understand the Hogdo powders do well over a range of temps (although I only ave mostly IMR).

But how do the accurate powders, Magpro specifically, do over big temp spreads. Ill be working loads up in summer for hunting in October. Hoping I dont loose considerable velocity.


I hear ball powders like win760 dont do as well over big temp changes and it looks like Magpro is also a ball powder.

Is ot the ball powders them selves or just certain formulations like Win 760?


Thanks!

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rcmodel
July 19, 2013, 11:34 PM
Don't over-think powder temp sensitivity.
It wasn't a consideration 20 years ago, before it became an advertising buzz-word.

If the load you work up is safe & accurate in summer heat?
It will be safer & just as accurate for winter hunting.

rc

slabuda
July 19, 2013, 11:53 PM
true just as, if not safer. But here in Idaho 400-500 yds is not uncommon on deer. I havent plugged data in to a program yet to see how much it changes drop at those ranges. I seriously do need to get a chrono so I am not just going by the load data velocity and shoot in hot/warm/cool/cold temps.

If I load up at 90* or even hotter as its Africa hot here lately and hunt on a cold Oct morning when its below freezing how much velocity could I loose 50 fps? not much 100fps+ changes things a bit.

slabuda
July 20, 2013, 12:10 AM
Just found a FAQ on Accurates website.

Copy/paste of specific section

"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."

3%-5% at 3200 fps is noticeable, BUT that is over a huge temp range of 165*. I am looking at maybe 80* max.

This is what I am looking for. Good data over a range of temps. So I guess if thats the type of temps manufacturers are testing over we dont see much at true hunting temps. I mean I sure as hell wont test loads up at 125*. 95* is too hot for me as it is. :)

GooseGestapo
July 20, 2013, 08:14 AM
Just remember;
If it's 95degF in shade, lay that ammo on a bench in direct sunlight, it'll quickly go as high as 145degF in a short time.

We have that problem here in S.E.USA all the time. I've had some ammo that was splendid in the morning in September at the NRA nationals at Jackson,MS. That afternoon, I had a picerced primer that disabled my gun, simply becasue the ammo was sitting in the sunlight (9mm Para, 115gr Sierra JHP, 4.6gr Bullseye, Federal Primer).
I've gone to slower powder (LongShot) and harder primers for semi-autos (Winchester).
The piece of primer lodged in my firing pin hole and blocked the firing pin. Lost 70 points and blew the match. With those 70points, I'd have won two guns !!! Expensive mistake!

I also keep my ammo out of direct sun light.
But, I've also set my magazines on the dash-board to warm them up on cold mornings too!

But, for hunting purposes, at under 300yds, it's not likely to cause a problem.
Where you can get into trouble is to work up the load when its under 30degF outside and later shoot the ammo when it's 100degF outside. (ie; prararie dog hunting, big-game/pig hunting in tropical conditions).

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