Temperature variations with H4350 and H4831sc range report 2

elkhuntr

elkhuntr

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Hi folks. Looking for some collective wisdom on the affects of say 10 degree temperature variations on a precision rig using Hodgdon extreme powder. I understand the H series powders offer better stability, but I believe I am seeing changes say from the 15 degree fall days to the winter 0 degree days or colder. Where you have a short accuracy node such changes could bump you out of it.

Are you seeing a change in half (or other) grain increments for every 10 degrees for example. What have you found in you load development. Your guidance is much appreciated.

Elky.
 
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I'd be surprised if you could see much measurable difference in velocity with small shifts in temperature, but when you attempt to use your summer load at -30, it makes a difference. Are you seeing changes in velocity or group size? As it gets colder we tend to bundle up in warmer clothing and the bulkier your clothing is, the greater effect it has on how you hold your rifle, which in turn could affect accuracy. Cold air is denser than warm air, and might show a few fps difference in velocity at the target, but I doubt it would be enough to change anything when we're talking only 10 degrees and a 10'-20' feet to the chronograph.
 
Run a controlled test that consists of soaking a few rounds of ammo at different temperatures for a couple hours, then shooting it over a chrono.

The problem with people's anecdotes about velocity change is that you don't really know what the temperature of the powder inside their cases was, (and neither do they). Depending on how the ammo was stored, transported and the exposure time, the temperature of the powder itself may be nowhere near what the temperature outside was.
 
Yes, I concede conditions and the nut behind the trigger play into the variables here. Looks like more testing to confirm.:p

Have you found higher nodes run more consistently? I am running a mild load 260 rem 130 berger currently at 2825 fps. Two other nodes above produced reasonable results, but not nearly to the accuracy of the lower node. It appears max or near max nodes work well in my hunting rigs, so would this thinking be consistent with your findings on a 30" barrel?

Perhaps another powder? I have not tried H4831sc for the 130s yet? Have you found this powder to be more forgiving or produce wider nodes in a 260?

Looks like just some more visits to the range with my chrony. :50cal:

Thanks
 
Hodgdon's line of extreme powder is supposed to be incensitive to temperature change however it seems they are a bit.
I used some 4350 and found it to give me less velocity when it got cold h1000 was worst.
 
kombayotch said:
Run a controlled test that consists of soaking a few rounds of ammo at different temperatures for a couple hours, then shooting it over a chrono.

The problem with people's anecdotes about velocity change is that you don't really know what the temperature of the powder inside their cases was, (and neither do they). Depending on how the ammo was stored, transported and the exposure time, the temperature of the powder itself may be nowhere near what the temperature outside was.
Click to expand...



bang on!
 
Jamie, ...your 260 threads are just great fun. Did you choose H4350 or H4831 for your projects? It appears to me if your node window is +/- 0.2 gr, then it gets a bit dodgy as I have found with my lower node testing.

I think its time to build some loads for my upper nodes and retest. I'm thinking 47.5 to 48.5 gr H4831 sc with 10 jump on the 130 bergers for starters. I found a H4350 node around 44.0 gr which provided flat strings, but just didn't test further (too tempted by the low node accuracy.)

Then I'll deep freeze em to see what happens just for fun. We are running in the positive degrees now and I am itchin to go to the range. Testing is fun...competition is the challenge:)

Thanks for the input guys.
 
I am testing H4350 with the 123gr in the 22" barrel

and 4831sc with the 139gr in the 29" barrel so far 45grs has shot very good
 
Elkhuntr, IMHO the H4831sc powder is better choice for your 30" long barrel than H4350 powder. Better jet I will tell you the best kept secret; try Belgium made temperature stable Ramshot Hunter ball powder with softest magnum primer available the CCI 250, friend of mine shoots his Rem 700 in 30-06AI with 180gr Barnes X bulets into one ragged hole at 100m with that combo and his is just hunting rifle.... My 2c, GR8.
 
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Range report: Here is some base line results for future reference.

Ok, here are some results with H4350 on my high node. Sighter pile Lapua 308 win brass used, bumped and full sized. 10 thou jump with 130 bergers, BR2 primer. Range shot at 300m, no wind (pulp mill exhaust going straight up). Mild but steady mirrage left to right. Temp hovering around 0 degrees. In short...awesome conditions.

Note, these are hot loads. Primers starting to flatten but still have rounded edges through the range of loads and no extraction issues.

43.7 gr. 3013, 2990, 3009. Avg vel 3004, ES23, vertical 3", group 3 1/4 Two shots within an inch, 1 cold shot high.

44.0 gr. 3033, 3032, 3025, 3010. Avg vel 3025, ES23, vertical 2 3/4", group 3 1/4 still high vertical.

44.3 gr. 3036, 3039, 3039. Avg vel 3038, ES3, vertical 1 1/4", group 2 1/4 This is .75 moa roughly. This load has promise to keep me in the 5 ring at 300m.

Evaluation: still a bit finicky but not unexpected with unformed brass. I expect some improvments based on fire fomed neck sized rounds.

It will now be interesting to see how H4831sc will do in comparison. And then I'll test to see the velocity differences on the best rounds at 10 or 20 degrees difference.

Cheers.
 
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Range Report 2: H4831sc baseline

Ok, here are some results with H4831sc. Lapua 308 win brass used, bumped and full sized. 10 thou jump with 130 bergers, BR2 primer. Range shot at 300m, no wind (pulp mill exhaust going straight up). Grey light day, no mirrage Temp hovering around 0 degrees. In short...awesome conditions again!!!!

Note, these are hot loads. Primers starting to flatten but still have rounded edges through the range of loads and no extraction issues. With sc, the compressed loads start at 47.8gr with my chamber.

47.5 gr. Avg vel 3010, ES10, vertical 1.921", group 2.081 .

47.8 gr.compressed Avg vel 3032, ES23, vertical 0.871", group 1.774. Best load coincides with H4350 load. 0.58moa load.

48.1 gr. compressed Avg vel 3053, ES24, vertical 1.996, group 2.098.

48.4 gr. compressed Avg vel 3057, ES22, vertical 2.126", group 2.126.


By the way, I shot my best f class rounds today with the low node load. 99-11v and 99-10v at 500m. So this is a good baseline for the conditions today.:dancingbanana::cool:

Now lets see how the temperature testing goes.
 
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Range report 3 15 degree test

Well finally got out in some nice spring weather.
My H4350 load of 44.3 gr with a 130 berger showed velocity within a couple fps (3037 fps with es of 2 on test day) from my 0 degree base line. However, interestingly the accuracy was poor on this test day.

Variables which did change from the winter test are that I found barrel touching so provided more gap in my stock. Also, my brass was showing some rather nasty donuts, so I neck turned them away. And the final variable is I was runing no bedding forward of the receiver. I recently re-bedded the nut and first 1" of the barrel.

So hard to say what caused the node change. But the accuracy was not up to par. The velocity however, is no change between 0 and 15 degrees.
 
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