Temperature Sensitivity with IMR 4831

Can't cite the source of this info, but here it is...again

The asterisk=degree

Imr3031 .73 fps per *
Imr8208xbr .59 fps per *
H4895 .23 fps per *
Alliant Varmint pro .89 fps per *
Alliant AR comp .77 fps per *
Varget .19 fps per *
W748 1.32 fps per *
Imr4064 .53 fps per *
Ramshot Tac .91 fps per *
CFE223 1.72 fps per *
Imr4895 .87 fps per *
AA4064 1.11 fps per *
AA2520 .98 fps per *
RL15 1.52 fps per * from 50* and up
PP2000MR .99 fps per *
Imr4320 1.32 fps per *
Ramshot Biggame .98 fps per *
H380 1.44 fps per *
VV N150 1.08 fps per *
H414/W760 1.42 fps per *
Imr4350 .64 fps per *
AA4350 .47 fps per *
H4350 .29 fps per *
RL17 1.42 fps per *
Hybrid 100v .78 fps per *
RL19 1.61 fps per *
VV N160 1.24 fps per *
Imr4831 1.19 fps per *
Ramshot Hunter .86 fps per *
H4831 .36 fps per *
RL22 1.71 fps per *
Imr7828 1.36 fps per *
Magpro 1.01 fps per *
H1000 .21 fps per *
RL25 1.59 fps per *
Ramshot Magnum .87 fps per *
Retumbo .49
 
I target shoot only now, my hunting days are done (a reapired back will do that to you, I am just gratefull I am mostly good if I am carefully with the weright moved and other day to day abuses)

That said, hunters come up to me all the time and admire my groups (many are not what I want but they are impressed)

I ask the, do you get your moose or caribou every year?

Yes (usually).

Cool, you are a hunter, I am a target shooter, the two have not a lot to do with each other.

When I hunted my rifle did 1.5 MOA. But it was consistent. No beater, no worse.

I missed one shot, because I did not trust my sight in and where I should aim (it was long range and I added some height and creased its back down the spine but not enough to shock it - which resulted in a trail of tears and a good story after it was all said and done but not during)

As long as velocity is in the area the bullets are intended for, 300 fps one way or the other makes no difference in bullet performance.

You simply do not need max velocity nor sub MOA to hunt with (I am talking 600 yards and less). Further out, then yes, you need to be a bench rest shooter.

I sighted my hunting gun in on the bench. I shot the game in various shooting positions depending on the situation, but I never had a shooting bench handy (hood of the Truck once on a highly illegal but safe road shot once)

Standing, kneeling, whatever got me a clear sight picture for a behind the shoulder shot.

If long shots are going to be taken, then you need to do your testing in the position(s) you are going to take those shots.

Because at that point its not the gun accuracy, its your ability to hold the gun to somewhere close to where you want to hit the animal.

Along with no shooting benches I never saw an animal with a target painted on its side nor did it have a display with its range from me.
 
As Said by others before- don‘t confuse impact of temperature between inner and outer ballistics. In cold conditions, powder burns slightly slower and velocity is lower. In addition, cold air is thicker and the bullet needs more force to cut through. Both impacts together are responsible for any shooting deviations.
 
Lots of good info. My main concern with Temp sensitive usually lay when you are pushing either side of the boundaries of a load. If you develop a load in mild to cool temps and its just at the threshold of pressure signs then on a warmer day that load can be dangerous. If it shot on a colder day ( as for the case in hunting mostly) I worry less since the speed will still have the bullet in the Minute of Deer threshold we crave as hunters. Now, on the opposite side, light loads...or those for recoil sensitive hunters where you are dancing at minimum speeds for expansion, and it gets colder...well you are risking a wounding shot vs a kill shot and less humane harvesting or worse.
As a rule of thumb, all my hunting rounds get tested at 0 F, 50 F and 80 F ( winter fall/spring and summer) here in Northern Maine. The rabbit holes we go down as reloaders is glorious :)
 
The other factor is that the exact amount of real drop in velocity with temperature varies with the cartridge. Varget temperature compensation works well in the .308 Win, but doesn't seem to do much in 223 Rem that I can tell. Denton Bramwell has an article on it, here.

For anyone interested, in Windows, if you have a keyboard with a number pad, hold down the Alt key while you enter 248 on the keypad and then let go of the Alt key (aka, Alt+248). The result is:

°, the degree sign.
 
you can get between "very cold" and "very hot" deviations in max pressure of up to 10%. If you pick your charge in normal conditions to stay at least 15% below max standard pressure you should be ok.
 
CAUTION: The following post (or a page linked to) includes or discusses loading data not covered by currently published sources of tested data for this cartridge (QuickLOAD or Gordon's Reloading Tool data is not professionally tested). USE AT YOUR OWN RISK. Neither the writer, The Firing Line, nor the staff of TFL assumes any liability for any damage or injury resulting from the use of this information.

To estimate that based on data from Hodgdon's site or from Lyman's manual, you can use my Excel file that lets you enter their data and test barrel length and your own barrel's length, and it tells you what you would get if your chamber and bore diameter matched theirs and if your lot of powder matched their test lot. There is no guarantee of that, of course, but it provides a starting point and you can see what percentage the particular powder would have to come down to lower expected pressure by a certain amount.
 
I have never quite bought into the temp sensitive idea. Most my load developement is done in the spring in weather I get by in in a light weight shirt. It's never caused me a problem when I've gone out hunting. Actually never gave the time of year much though to developing loads till I started reading about this temp sensitive stuff and then pretty much shrugged it off. Sit at the bench trying to develope a load in freezing weather and you freeze your chalones off! Do it in 80* or more weather and you not only sweat all over yourself but you fire two shots and the barrel stays hot the rest of the day!. I don't doubt there some truth to the table above but I don't think the effect has a lot to do with hitting and missing a target! and I doubt it will have much to do with moving a load over max and blowing your gun up in hot weather either. raise and lower pressure a bit, probably so but unless you do your loading it 10* weather and hunt in 120* weather there just isn't much to worry about! But in the view of a powder salesman, temp sensitive in powder is a good selling point!
 
A lot of the concern is regarding long-range shooting. Snipers, in particular, have to be aware of the long-range effect on vertical POI as they often get only one shot. For hunters shooting medium or larger game within 400 yards, and who haven't loaded up to the absolute top end maximum for their rifle, it isn't normally going to be as big a factor as the hunter's ability to hold.

For people who do load up near the top, it can be an issue when things get warmer. The Army apparently had problems with M118 LR, which used a version of Reloader 15, giving overpressure signs in the desert where 120° temperatures can occur during the day. So it is an application-dependent thing.
 
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