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Powders & cold weather

A-con

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Dec 23, 2000
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I've been useing IMR 4350 for years. It works well in my three main rifles, 7mm-08, .270 Win & .338 Win Mag. I'm concerned about how the loads will preform in very cold weather. Most of my load development is done in the summer at 80% to 100%, and some of my hunting is in very cold, like below 0%. I gess it won't matter if the animal/target is 100 yds away, but if it's a long shot like 400 yds+ a hundred FPS could make a big difference in the point of impact,
any thoughts or suggestions ?
 

T Bone

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Anaconda,
IMR4350 is fairly stable from what I've seen. I too use it in a variety of rifles. 300 win, 30-06, and now 270.

I do know from experience H4831 does weird things in extreme cold. Pressures increased in my loads in my 30-06 while shooting at a desert muley in -10 weather, I shot two rounds. The first (missed) enlarged the primer pocket the second (dead buck) casing stuck in the chamber.

If anything, I'd of thought the pressures would go down with cold temps.

If I remember correctly DANR55 had some scientific explanation for it.

T Bone
 

danr55

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Dec 18, 2000
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Yep.. when the weather gets cold, you'll find that chamber pressures increase. Contrary to most peoples explanation of Boyle's Law and how gasses act in lower temperatures. They forget the Boyle's Law deals with gas in a free state and not the pressure differential experienced with gases exiting a confined container. So what all that boiles down to, (pardon the pun) is that if you are loading close to max in warm weather, chances are in cold weather you will be over pressure. So it's always best to test fire your rifle in as close to the hunting temp as possible. Don't store your ammo outside if the temp is really low or you could be in for a rude surprise.

Dan, as for the IMR 4350, it's pretty stable. The reaction of the powder doesn't change much. If you are loading close to max, the change in pressure differential could have an adverse effect on the performance of your rifle. If your loads are not close to max, then chances are you have little to worry about. Take a minute and shoot it at a target before you take it hunting.

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A-con

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Thanks,
My problem is where I live it's HOT (kinda like Mesa) in the summer, even if you get up to the range early, it can be 80% + by 8:00am. Last season, hunting elk with DS, it was like -10% when I pulled the trigger.
One of these days I'm going to get a long shot. I gess I'll stick with IMR 4350.

<FONT COLOR="#800080" SIZE="1">[ 05-07-2003 21:16: Message edited by: Anaconda ]</font>
 

1_pointer

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Dec 20, 2000
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Indiana
Hodgdon sc powders, Reloader 15, and Ramshot are purported as being the least dependent to temperatures, according to Barsness.
 

Calif. Hunter

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Dec 13, 2000
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Apple Valley, CA, USA
I experienced blown primers with IMR-7828 at 0 degrees or below with a load that was okay at 70 degrees. I still like that powder best for my .300 Wthby. I use RL 22 for my .338 now, with IMR-4350 as a second choice.
 

danr55

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IMR 7828 is what I traditionally use for my 264 win mag. It does react differently in cold weather.

Another area of concern when moving to extreme cold temps is the caliber of the weapon. Calibers like the 264 win mag tend to go critical very quickly. That is to say that 1/2 grain of powder can make an extreme difference when you push the load to max. Other magnum calibers like the 338 win are not quite so sensitive. It all adds up to being very careful when you load and load appropriately to the conditions you will be shooting in.

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Yeti

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