temperature stable powders (precision rifle)

Precision Rifles » Ammunition and Ballistics

dodpilot

Joined Apr 2017
Posts 33
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IL, USA

Posted: 8/5/2017 6:19:52 PM EDT

At what range should I really be concerned about the effects of temperature on my handloads for .338 RUM, .338 Lapua, and .270 Wby Mag when hunting in the field?

I spoke to a tech at Alliant Powder yesterday who stated:

~600 yards is the breakpoint for benefits in using a temperature stable powder (per Berger Bullets). At yardages prior to that, the deviations in velocity (and therefore vertical stringing on target) are effectively inconsequential.

My intended max range for deer-sized game (Dall Sheep) is ~ 400 yards. 600 yards would be a high-altitude, thin air, perfect hold, zero wind exception.

Anyone want to add any personally-learned experience?

- CS

taliv

Joined Jul 2004
Posts 1636
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TN, USA

Posted: 8/5/2017 9:41:36 PM EDT

[#1]

granted, it is technically rocket science, but it's pretty easy to figure it out for yourself because there are calculators that do the math for you.

grab your favorite ballistic calculator and figure out your dope at 600 or 400 or whatever. now change your MV by 100 fps or so and see how much your POI changes at 400 or 600. Does that put you outside your kill zone for a sheep?

the worst powder i know changes about 1.7 fps per degree F change. so if you zeroed at a like 90* and then shot in 30* on a mountain somewhere, that would be 102 fps change. the best is about .5 fps per degree F change, which would only be a 30 fps change.

dodpilot Joined Apr 2017 Posts 34 EE 0% (0) IL, USA	Posted: 8/5/2017 9:47:02 PM EDT [#2] That makes sense. Thank you, wilco.

Harv24 Get off my Lawn!! Joined Dec 2003 Posts 11826 EE 100% (205) WI, USA	Posted: 8/6/2017 1:18:34 AM EDT [#3] IMR4064 was chosen for the MK318 rd due to its stability to temperature.
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TeeRex

Short Armed Skinny Jean Wearing Hipster

Joined Oct 2009
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OH, USA

Posted: 8/8/2017 8:57:36 AM EDT

[#4]

A lot of stuff shows up beyond 600 yards. Pretty similar to having a poor ES/SD. A lot of stuff will look good until you get put beyond that range. It is also equally important to know your Density Altitude, but again big changes in that don't start to show up until longer ranges.

I personally think stability is important for consistency. Loads that are developed with a temperature sensitive powder can also become dangerous if not tested in extremes at the worst, or they can be pushed out of a node and become inaccurate.

I got it at the Costco.

robpiat Joined Jan 2003 Posts 9165 EE 100% (121) GA, USA	Posted: 9/3/2017 10:34:08 PM EDT [#5] its not just the elevation variation. the concept of finding the right accuracy node for a given bullet centers around low variations. I've got loads that could swing +\- 1 whole grain and still group well. I've got others where .3 grains is poor groups.

Firestarter123 The original Murder Bunny© Joined Jun 2007 Posts 11954 EE 100% (143) NE, USA	Posted: 9/4/2017 10:11:07 PM EDT [#6] My 10-shot average for my 178gr ELD-X load changed 3fps going from 70F to 100F using Varget. I was shocked!

taliv Joined Jul 2004 Posts 1645 EE 0% (0) TN, USA	Posted: 9/6/2017 12:32:00 PM EDT [#7] jf, it's typically non-linear. you may see a lot more change going from say, 60 to 30 or 30 to 0

Firestarter123 The original Murder Bunny© Joined Jun 2007 Posts 11960 EE 100% (143) NE, USA	Posted: 9/6/2017 5:11:11 PM EDT [#8] Interesting....I will have to grab the Magnetospeed when it starts to cool down and see what happens. I have never had a chronograph but I was just happy with the results going from 100F to 70F since that is where I do most of my shooting.

popnfresh

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Joined Oct 2005
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TX, USA

Posted: 9/7/2017 9:20:00 AM EDT

[Last Edit: popnfresh] [#9]

I am not understanding the range thing in relation to temp sensitivity. 600 yards?

Makes no sense. Is this for people with zero velocity data on their load?

I use W760, it is horribly sensitive to temp, but it works fine at 35° 2325fps and 95° 2425fps. There is no change at 600 yards or 1060, nothing shows up.

It is simple to deal with, I just have 2 loads for the same load in my solver. One for 30-70° temp corrected and one for over 70° temp corrected(not linear).

I suppose I could see for hunting or military where it may be difficult to keep your powder at ambient temp.

Did this test a while back with W748.

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Rex_Allen I am not a brony!!! Joined Jul 2013 Posts 1673 EE 100% (7) AZ, USA	Posted: 11/1/2017 7:01:02 PM EDT [#10] Quote History Originally Posted By jlficken: My 10-shot average for my 178gr ELD-X load changed 3fps going from 70F to 100F using Varget. I was shocked! View Quote @jlficken what’s your load for the 178 eldx and what velocity? I’m also using varget and eldx
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Firestarter123

The original Murder Bunny©

Joined Jun 2007
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NE, USA

Posted: 11/2/2017 3:06:06 PM EDT

[Last Edit: Firestarter123] [#11]

Quote History

Originally Posted By Rex_Allen:
@jlficken what’s your load for the 178 eldx and what velocity? I’m also using varget and eldx

View Quote View All Quotes

View All Quotes

Quote History

Originally Posted By Rex_Allen:

Originally Posted By jlficken:
My 10-shot average for my 178gr ELD-X load changed 3fps going from 70F to 100F using Varget. I was shocked!

@jlficken what’s your load for the 178 eldx and what velocity? I’m also using varget and eldx

@Rex_Allen

I am shooting an Accuracy International AT w/ 20" factory LW barrel.

Here is what I gathered when I shot last at 70F. It didn't change enough to matter when I shot at 100F.

MemeWarfare

Joined Oct 2010
Posts 3171
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USA

Posted: 11/2/2017 3:58:03 PM EDT

[#12]

Quote History

Originally Posted By jlficken:
My 10-shot average for my 178gr ELD-X load changed 3fps going from 70F to 100F using Varget. I was shocked!

View Quote

Varget is amazingly temperature stable for its age. I'm a big fan.

To contrast, I worked up a .25-06 load with R22 and tested mv from 34F to 100F in 10 degree increments. There was almost 180fps difference across that spectrum.

bfoosh06 Member Joined Sep 2008 Posts 6194 EE 0% (0) NT, USA	Posted: 11/10/2017 11:58:10 AM EDT [Last Edit: bfoosh06] [#13] Just saw this last night... I don't know how accurate it is ( or for that matter who is the author ) , but it is food for thought.
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