Home Forums Hunting & Shooting Ask The Gunwriters Mule Deer & others-Least temperature sensitive slow burning powders?

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In summary, based on very limited experience, I've run out of space in Federal brass before I hit pressure. Velocities have been good, but not better than TAC in the 185 TTSX.

I find this to be the simplest explanation, and also the one which best explains the extremely variable results. I refer here to how some loads will exhibit let's say an 80 to 100 fps difference and have a half inch change in POI. Another load will show about the same velocity difference, but POI will move inches in 2 different directions. That's a clear harmonics issue, to me. In essence,then, the original load may shoot well, but it's a 'fragile' load in that a tiny change in anything at all will destroy its performance.

All of us have had the experience of accuracy AND point of impact changing noticeably when working up loads with some rifles--while in others point of impact remains very similar even with varying charges of the same powder. Often the most consistent rifles have heavier barrels.

In my experience, the same rifles that show wide variations in point of impact when working up loads at, say, 70 degrees, are the same rifles that will change POI at different temperatures--unless loaded with very temp-stable powders.

I agree with your observation that thinner barrels will usually whip more, and I also agree that managing variables can be more important for some rifles than others. Where I think we disagree is on the universality of the notion of temperature stability of a given powder (see the Bramwell article), and therefore the confidence one should place in such claims/notions, and also about how much explanation or discussion is warranted when we talk about the various factors that impact POI.

I haven't read the Bramwell article yet, but I don't place absolute faith in temp-stability claims of any powder--and have posted to that effect many times, because of my own test.

In fact many powders will vary in their temp-stability depending on the specific cartridge and bullet, which is why I have also advocated test-shooting at the temperature you might be hunting at no matter what powder you use.

H4831SC, however, has tested well so many times in varying conditions, and in several cartridges, that I do tend to place a lot of faith in its ability to deal with temperature changes, especially cold.

MD,

Do you know if "regular" H4831 mirror this charactoristic of the SC version?

DakotaDeer,
Where are you? The Dakotas? Given the question as posed, I would recommend taking a 20 rd box of both temperature ranges and a small wind guage with a built in thermometer. Barring that take a box of the lower temperature range and hunt early morning and late afternoon with a break in between to enjoy nature and rest up for the late afternoon to dusk hunt.

Flower Child

SOTG,

Hodgdon claims it does. I haven't any regular H4831 in a long time, though, so haven't tested it.

Thanks, was wondering as the last time I made a trip to Powder Valley they were out of Short Cut and I had to buy the Original. OTOH it rarely gets that cold down here during deer season and if it did I'd probably follow Sam's advice and set in the house, crack open another Smithwick's and wait until the next day when it would likely be 40.

Can't hurt to start with the powders that have proven themselves even in dubious tests. More field testing needed.

But I am still going to retain the right to claim the first shot was just a warning to alert the game to be more sporting, the second is to warm the barrel properly, then the third is all business.

Do you still use a regular drop measurer? If so, I think that leaves two of us.


Travis

I noticed this years back when I used to use IMR4831 extensively in both the 270 Win with 130 gr bullets,and the 7RM with 140's;the powder showed greater velocity losses in winter temps(below 20F) in the 7 RM than it did in the 270 Winchester,in which it was pretty consistent....for some reason...

Has any one used H4831SC in the 257 Roberts? I thought to try that as from this discussion H4350 is a bit more temperature sensitive?

Travis,

Actually, I know quite a few handloaders that still use mechanical powder measures--including most of the gun writers I know--and for very real reasons that I ain't going into here.

jimmyp,

In my own tests, H4350 has performed very well in cold temperatures. I first tested it in the 7x57 with 140's. At 70 degrees the load chronographed 2842 fps, and at zero it chronographed 2832 fps. Point of impact was unchanged, and in both tests the rifle grouped three shots under an inch.

I also perform temp-tests every time I go to the range, noting the temperature that day in my loading notes. I regularly shoot in temperatures ranging from 25 to 90, and H4350 has performed very reliably in that range.

As I've pointed out earlier in this thread, even temp-insenstive powders will vary in performance with the cartridge and load. In particular they can get a little wonky if loaded to the ragged edge of pressures, especially in a cartridge where a little slower powder might work better. The primer can also make a difference in really cold weather (and here I am talking about tests done with everything cold, not just the ammo).

At any rate, if you're really worried, H4831SC does work very well in the .257, especially with 155-120 grain bullets, though it also works pretty well with 100's.

I'm a Redding BR-30 user. For big charges I throw half twice.

Which is still quicker than any electronic measure I have ever seen.

It's also hard to use an electronic powder measure on a progessive loader....

Mule Deer,

You (and others) mention that the temp. sensitivity varies with the cartridge. Have you ever done any testing with the 6.5x55? If so, what powders stood out there?

H4831SC works very well in the 6.5x55, and as mentiond earlier in this thread is one of the most reliable temp-resistant powders. I've also had great luck with H4350, especially with bullets in the 120-grain range, even in very cold weather.

This is a very informative thread. It prompted me to finish a hot vs. cold test I started two winters ago.

The two best loads for my 26" 257 Weatherby with its most accurate bullet, the 117 gr. Hornady SST, use IMR-7828 (68.5 gr) and Ramshot Magnum (73.0 gr). Using Fed 215-M primers and an OAL of 3.190 both loads give sub-MOA accuracy with velocities in the 3300-3350 range (at normal temps) and nearly endless case life in Norma brass.

In an effort to find out which load was the "best", I loaded one lot of cases, half with each powder, and shot half of each through the chrono on as cold of a day as I get here (32 degrees). Then I set the rest aside to wait for a hot summer day. This thread reminded me of my test so yesterday I broke out the ammo and shot the rest through the chrono at 92 degrees. Here is what I got:

IMR-7828 SSC (68.5).... Ramshot Magnum (73.0)
92 degrees 3370 fps.... 92 degrees 3354
32 degrees 3318 fps.... 32 degrees 3285
difference 52 fps.... difference 69

IMR-7828 SSC came out the winner but you can see that both of these powders did pretty well. I should add that POI did not seem to change a noticable amount. Other testing with these two loads at long range since I fired the cold string had given the edge to the IMR-7828 SSC, since it grouped about one inch smaller at 400 yards than Magnum did (3 inches vs. 4 inches).

This rifle, a Mark V, made me a believer in Ultra Bore Coat, and it was a two-MOA rifle until I gave up the free-float and added fore-end pressure. I credit JB for much of the success and enjoyment I have gotten from my shooting from his articles and sharing his knowledge on this forum.

As to velocity loss with lower temps, I read an article once that gave a rule of thumb: "On average you will gain or lose one fps for each degree of temp change". I don't remember if the writer was talking about any particular group of cartridges or powders. Since I do lots of testing and almost every round goes through the chrono with the temp recorded on the data sheet, I have found this rule of thumb to be fairly true with the guns that I shoot at relatively moderate temperature. I also learned when you arrive in Montana for your hunt and the temp is near zero you had better confirm your drop figures by actually shooting at the longest range you honestly want to call your limit. I also learned those big Montana critters in that clear air in wide open spaces can be a lot further away than you think. And a relatively flat shooter like the 257 Weatherby won't make up for poor judgement. Thank you, JB, for helping keep me steered in the right direction.