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Powder temperature sensitivity

 
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  #1  
Old 11-29-2009, 10:08 AM
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Join Date: Jun 2009
Location: Merkel, Texas
Posts: 55
Powder temperature sensitivity

Fellow shooters,

I've mostly used Hodgdon, because that is available locally. IMR powders I've used were much "milder" in freezing temperatures. I want to improve velocity in one cartridge, and the manuals show Ramshot's Magnum powder and Accurate's Magpro powder to give 150 to 200 fps more velocity than what I can currently get with either H4831 or H4350... The Hodgdon based velocities are measured on chrono. RL17 proved to shoot a full 200 fps faster in this cartridge than either Hodgdon powder used. I've read several threads about the RL17's temperature characteristics, but nothing on the Magnum or Magpro powders. What I MUST know is: What is the relative temperature sensitivity of each of these powders??? I ask because I must work up the loads near 75 degrees, yet hunt at freezing or below. Which will be more stable throughout the temperature range??? Who can help???

Thanks,

Coach
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  #2  
Old 11-29-2009, 06:32 PM
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Join Date: Aug 2003
Location: NC, oceanfront
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Re: Powder temperature sensitivity

Nobody knows their temperature sensitivity without testing it in their gun. This is what you will have to do.

Or, you can keep ammo in your pocket, and load single shot -just prior to taking a shot in cold temps. With that, you have only the POI change from a colder barrel. This could still be significant if not cut-rifled.
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  #3  
Old 11-29-2009, 08:01 PM
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Join Date: Dec 2001
Location: Winterville, NC
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Re: Powder temperature sensitivity

Hey Coach,
I use alot of different powders year round, with the exception of AA and Ramshot, and I notice a little difference in velocity, but not alot. I usually adjust my Ballistic Card according to the conditions I'll be hunting in.
For instances; if I'm hunting groundhogs with my .243 Win and a Hornady 75gn HP/IMR 4895 in 90-80 deg temps., first thing I do after I've found an accurate load is chrono that load at that temperature, and at the same time check my zero. For "whistlepigs" I like the zero to be approx. 3-3.5" high @ 100yds and dead on at 300yds. I make my card up and use that as long as the ammunition last, the conditions persist or the groundhogs wave a white flag .
After I print out that data, I cut only the necessary info out, write the load data on the back (i.e. cartridge/bullet/powder/primer/case/OAL/velocity/date) and the atmospheric data (i.e. wind/temp/humidity/barometric pressure), then I laminate it so it can easily be taken and replaced from behind the nylon cartridge carrier on my rifle stock.
Later, if I switch to the 95gn Ballistic Tip/Viht N560 in 60-50deg temps., I make a card for that only after I chrono the most accurate load.
This is not the preferred method for everyone, but it works great for me, it's quick and it's accurate. JohnnyK.
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Old 12-08-2012, 10:39 PM
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Join Date: Apr 2011
Posts: 1
Re: Powder temperature sensitivity

I have been shooting Magnum powder through my 338 Lapua for over a year now. I love this powder as I have shot many groups placing 3 shots being covered easily by a dime. Loads also prove to be very stable & consistent with an SD of 3 on a 4 shot string. I also have been looking for some info on temperature stability on this particular powder. Please see the link I have attached & you will see that according to Barnes testing this powder proved to be a very thermally stabile powder.

Hope this helps???

July 2010 Barnes Bullet-N | Barnes Bullets
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  #5  
Old 12-09-2012, 08:58 PM
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Join Date: May 2012
Location: N.D.
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Re: Powder temperature sensitivity

Quote:
Originally Posted by Mikecr View Post
Nobody knows their temperature sensitivity without testing it in their gun. This is what you will have to do.

Or, you can keep ammo in your pocket, and load single shot -just prior to taking a shot in cold temps. With that, you have only the POI change from a colder barrel. This could still be significant if not cut-rifled.
+1,
but if you are at -10 degrees with a wind your pocket will still be at freezing. You should shoot at the temp you will be hunting at to be sure, but I realize this isn't always possible. If I couldn't hunt with a load I'd vetted in both hot and cold temps. I'd go with THE ONE THAT SHOWED THE LOWEST ACCURACY FALLOFF AS I DROP THE CHARGE WEIGHT, and I'd hope for a slight gain in accuracy. If your load is see-sawing between great and crappy accuracy as it pulls in and out of node when you pull the powder charge up, the load is crap and I won't touch it period.
Don't use a mild primer either, as under igniting will cause a squib on occasion-- with a bullet in bore chance, or poor accuracy at least with long lock-time. Over- igniting with a hot primer just pushes your pressure up a bit.
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