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Old December 5, 2012, 03:06 PM   #1
Eppie
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Is Spherical Powder More Sensitive to Hot Climates than Other Powders?

Hi Guys,
I've recently started reloading and because I have a Hornady AP press I've settlled on ball powder because its easy to measure. With Varget and IMR I was getting too much variance on my powder measure.

A few days ago, while at the range, one of the guys mentioned that he tried ball powder in the 80s but gave up on because the Houston sun would cause "flashing" if bullets were left exposed to the sun. A lot of things have changed in the past 30 years.

The question is this: Is spherical powder more sensitive to hot climate then other powders?

Thanks for your advice.
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Old December 5, 2012, 03:28 PM   #2
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Ball powder is more sensitive to temperature. That doesn't mean, however, that you need to develop a load for every 5 degrees of temperature variation though.

If you are shooting long distances over a wide variation of temperatures (think something like from -10 as the low extreme up to 100+ as the high extreme), then you would probably need to assess the different characteristics for low, medium and high temperatures. Outside of that though, it's really not something you are going to notice.

Military powder is WC844 and WC846 for 5.56 and 7.62, both of which are ball powders - and they manage to work just fine from the hot deserts of Iraq all the way up to the higher elevations in the Hindu Kush.
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Old December 5, 2012, 04:21 PM   #3
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How the powder meters out of the measure makes very very little difference at 300yds and less.
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Old December 5, 2012, 04:42 PM   #4
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IME, Ball powders are sensitive to low temps ...... dunno about the other end of the spectrum.
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Old December 5, 2012, 09:06 PM   #5
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From AR15.com

Several years back Hodgdons did a velocity spread test from 0-125 F on 7.62x51mm using a 168gr OTM bullet. Their data showed the most temperature sensitive powder in their test to be IMR 4895, not a ball powder. Hodgdons data was on their website but has since been removed. I have had no luck in getting Hodgdons to send me their full list of data from their tests. A partial list of the Hodgdons data is below:

Velocity spread in FPS between 0-125 degrees F:

1. H4350: 4 (FPS)
2. Varget: 8
3. H4831C: 10
4. RL 12: 26
5. AA4350: 29
6. AA2460: 36
7. IMR 4064: 46
8. VIT 550: 49
9. RL 15: 50
10. VIT N140: 50
11. AA2520: 63
12. IMR 4350: 67
13. RL22: 75
14. RL 19: 94
15. AA3100: 113
16. W 748: 114
17. VIT N560: 121
18. IMR 4831: 127
19. IMR 4895: 166
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Old December 5, 2012, 11:23 PM   #6
Eppie
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I guess that what everyone is saying that I really shouldn't worry about the comment about ball powder being heat sensitive.
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Old December 6, 2012, 02:36 AM   #7
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Never had problems in the Mojave Desert in 110+ degree weather with W231, W296, W748, AA#2, AA#7, AA#9, etc. etc. showing sudden pressure spikes or destroyed actions in over 20 years of reloading. Ball powders have been around for well more than 30 years...they were used in Vietnam.

Follow good loading practices and you'll have no surprises due to high heat.
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Old December 6, 2012, 08:53 AM   #8
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SHR970

Thanks SHR970 for the advice, if you have had no problems then I'm going to rest easy.

I had "assumed" that Winchester with their long experience would not bring a product to market that posed that kind of a problem, but it's always nice to get confirmation from another user.
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Old December 6, 2012, 04:43 PM   #9
edward5759
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Heat here in Arizona and ball powders

I load all ball powders, except several rifles that don't like it.
Here in Arizona where it can get to 120 and in a vehicle up to 190 degrees!
I load in the winter, to day its 82 degrees, and when I shoot in the summer High Power Matches CMP i don't see a lot of difference out of an M14. When I was shooting off a cement bench I would see more of a difference in groups would open up a little.
My friend said he saw more pressure signs but nothing to blow his gun up.

Edward5759

Hope this helps?
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Old December 6, 2012, 05:00 PM   #10
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Edward,
Thanks for taking the time to respond. Your input is appreciated.
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Old December 6, 2012, 05:09 PM   #11
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We shot 100 match loads for .308 win last week, for a long range rifle course we host here in SW Virginia.

The 44.4 grain charge of W748 behind Nosler 168 grain CC bullets did fine. Velocity was a tad over 2700 fps from a 24" barrel, and this in 40 to 42 degree F temperatures. (and as an aside, the 1000 yard target was no problem for this load, turns out...)...

That load does not go 2850 fps in warm weather, I assure you.

The hypothetical and anecdotal data being tossed around the 'net is just that: hypothetical and anecdotal--most of the time.

If someone does a test to see what the velocity loss is from 100 degrees F to -20 degrees F, there is much more to be considered than we often see.

Was the velocity drop linear, respective to temperature? Or did it stay pretty stable all the way down to, say, 30 degrees and then drop hard? Or did it drop 80 fps from 100 degrees to 85, then stabilize all the way down the board?

Over the years, I've found that most information shared as to temperature sensitivity, or cleanness of burn, or lot-to-lot consistency is based not on personal experiences, but rather on what has been read elsewhere.

Powders can be more or less temperature sensitive based on load density as well. For instance, in a large temperature drop, you'll get more of a velocity loss with W748 on low density loads than on higher density loads, even though it's the same powder and same lot. There's a certain air to powder ratio in the case that's going to affect the overall pressure curve relative to temperature.

Also, proper load development cannot be over-emphasized. An OCW load (google "dan" and OCW) will show less temperature sensitivity than a non-optimal load. And by the way... just because your load shoots accurately most of the time, that doesn't mean that it's an OCW load.

Too, the "extreme" rated powders can have issues of their own. They tend to be harder to light, and therefore prefer high load densities which keeps a firm portion of the powder column pushed back against the flash hole. Extreme velocity spreads increase as load density goes down. However, there are other powders which have reputations for being sensitive to temperature than give fantastic ES numbers in lower, safer, and more comfortable to shoot densities.

So there's a lot to consider. I like W748, and I like IMR 4895. I prefer IMR 4350 to H, but use both.

The best thing to do is develop your load, and gather your hot and cold weather data in the field, rather than on the www.

Dan
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Last edited by Dan Newberry; December 6, 2012 at 05:17 PM.
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Old December 6, 2012, 08:39 PM   #12
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Yes, and not all spherical's are alike either. CCI changed their magnum primer formulation in 1989 to accommodate the needs of the military WC8## series of St. Marks powders. Talking with a Western Powders tech, I learned the coatings on newer offerings like the Ramshot line have more modern coating chemistry that doesn't need the warmer primer for best ignition consistency and they have more temperature stabilization. So you really can't generalize too much about this. Also, Denton Bramwell showed barrel temperature mattering more than powder temperature in tests here.

The stability really does change with starting pressure and peak pressure. Hence the case fill effect. The best common example (I think maybe Denton mentions it) is Varget doing very well about apparent temperature stability in the .308, but being no better or worse than a number of other powders when used in the .223. When you think about it, because rate of change in pressure is determined by the powder progressivity curve interacting with the rate of expansion, chamberings that have different expansion ratios and different average velocities will not be needing the same temperature compensation. So there's really no one-size-fits-all temperature compensation scheme.

Hodgdon's comparative data for some powders in their Extreme line that Mahevey posted isn't all fired in the same cartridge with the same average muzzle velocity. If you take the variations as a percentage of average muzzle velocity for the individual cartridges, the worst/best thing can change order.
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Old December 6, 2012, 09:30 PM   #13
Eppie
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Uncle Nick & Dan Newberry

Uncle Nick & Dan Newberry thanks for contributing to my question. Obviously you both bring a lot of knowhow to the table.

Dan, I have bookmarked your OCW web site. Looks like there is a lot of meat there and it may take some time for me to read and digest all of that.

Uncle Nick, it's interesting that you mention Ramshot TAC. I just discovered it by talking to the Sierra Bullets tech guy, and after looking it up I discovered that it is also about $30 cheaper for an 8 pound can then Win 748 or 760. I think I am going to give it a try in the near future.

Gentlemen, I commend you both on your willingness to share your wealth of knowledge.

Kindest regards.
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Old December 7, 2012, 04:13 PM   #14
Eppie
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Dan Newberry

Hi Dan,
I've been reading through your OCW web site. Excellent job. There is a lot of good stuff there.

I'm going to send you my $45 for your consulting. I too want to get my ammo's accuracy optimized for my rifles.

You should stick the info in a pdf so people can read it, print it and refer to it. If don't have a way to create a pdf let me know and I'll do it for you and send it to you.
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Old December 7, 2012, 04:28 PM   #15
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here's a link where someone converted it to PDF and posted it...

http://www.twincityrodandgun.com/PDF...%20-%20OCW.pdf

The Iowa State Rifle and Pistol Association also has a PDF of it, somewhere on their site.

Thanks for the kind words.

Dan
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Old December 7, 2012, 05:29 PM   #16
Eppie
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Dan

On Your site first paragraph says
Quote:
This does not necessarily correspond with the tightest velocity figures, however.
I assume you mean "highest" not tightest. Am I wrong?

Thanks
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Old December 7, 2012, 05:35 PM   #17
Dan Newberry
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no, it really is "tightest"...

Lots of folks just shoot across a chronograph looking for the tightest numbers (lowest extreme spread)... and they go with that load if it seems accurate.

You can reduce ES after you find the OCW (optimal charge weight) for the powder.

I don't use a chronograph at the initial load development stage, except in certain rare circumstances.

Dan
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