Temp sensitivity - Alliant powders (RL19, RL22 etc)

todbartell

todbartell

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just curious if any of you guys have chronographed loads with Alliant powders in warm temps & cold temps.

I usually use Hodgdon powders, due to their claimed insensitivity (Extreme line - 4350, varget, 4831sc etc), but honestly have never tried chrony'n them in different seasons...I just take Hodgdons word for it :p


anybody?
 
I lose about 200 fps with RL-10 in my 204 at -5 (as opposed to +25). With Varget, I lose a bit, but it's less than 100fps
 
todbartell said:
just curious if any of you guys have chronographed loads with Alliant powders in warm temps & cold temps.

I usually use Hodgdon powders, due to their claimed insensitivity (Extreme line - 4350, varget, 4831sc etc), but honestly have never tried chrony'n them in different seasons...I just take Hodgdons word for it :p


anybody?
Click to expand...


Once it gets cold out I may try chronographing just to see what happens. Some chronographs say not to use them below freezing, and Oehler claims my machine will work to -18C, but colder than that all bets are off. The problem might be whether or not to believe the reading at cold temperature.
 
4831

I tested IMR4831 & H4831 in a 30-06 Winchester Model 70/24 inch barrel.
Rounds fired at 20C and chrono'd. Same loads fired at 0C that fall.
IMR loads lost 90 FPS. H4831 loads lost 25 FPS.
IMR load started at 2890 FPS
H4831 load Started at 2900 FPS
Seems less temperature sensitive to me.
Carry on!
 
The claim by Hodgdon seems realistic based on my shooting from summer to hunting in winter.

I try and work up loads in the spring and/or early fall so temps are not at either extreme. I shoot throughout the year and my drop charts stay bang on.

If there was any velocity changes, the drop charts would change especially beyond 600yds.

For alliant powders, the only one I have experience with is Re25 in my 7RM Savage. So far, this has stayed stable too but I don't hunt much below -5C

Jerry
 
Have had good accuracy and consistant ballistics with Alliant, usually chrony my hunting loads @ the temp I will be hunting in so do not have good data from hot/cold. Would use Alliant before Hodgdons.
 
Boomer said:
Once it gets cold out I may try chronographing just to see what happens. Some chronographs say not to use them below freezing, and Oehler claims my machine will work to -18C, but colder than that all bets are off. The problem might be whether or not to believe the reading at cold temperature.
Click to expand...

You might try chilling the ammo (e.g., in a bag in a thermos with some ice)
 
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When I hunt coyotes, the temps drop to -25C with a wind.

I find that the Norma powders like N160, N165 or the ball powders like W760, don't vary a lot. There is some velocity drop though and your only alternative i'm afraid is to get enough of a lot of powder to try at differnt temperature extremes. Varget is supposed to be very foregiveing, but I don't use enough of it to say.

H4831 is frankly terrible as is Re-19 and Re-22.

Not only that, but each lot of powder reacts slightly differently form the last. Your best bet is to buy enough of one lot that you find accurate in your rifle and keep records at a certain distance like 200-300meters, every other range will be proportionate to the ballistic charts available in the manuals from there and also give you a pretty good idea of your velocities at the temp range you're shooting. A long drawn out process, but worthwhile.

Also email the manufacturers with your loads and cartridge specs, they should be able to provide you with exactly what you want, give or take 50 fps. They are usually only to glad to help.

bearhunter
 
Bearhunter, I'm not trying to flame you but an observation about your post....
"When I hunt coyotes, the temps drop to -25C with a wind. "

Temperature "with the wind" means NOTHING. Actual thermometer temperature is what affects the burning rate of powder and hence velocity. Ever since Environment Canada stopped reporting wind chill in watts/sqare meter and went to the stupid "feels like" system of temperature reporting many people get confused about rate of heat loss versus temperature. Rate of heat loss does not matter to a rifle.
 
I gave up using ReL19 about nine years ago partly because it seemed that velocities would alter very significantly between 0 celcius and 25 celsius. I forget exactly what calibres I was using it in but that is what I found - differences in the 100 to 150fps range. I wonder if today they make it better in this regard (???).

The ReL 15 I use now in various rifles does not seem to evidence the same extreme temp senesitivity.
 
What the heck did we ever do before someone thought up the temperature sensitivity issue? Sheesh, there is a bit of change with temperatures, but you should shoot your pet load in the temps you are going to hunt in to find out what difference in drop, if any, exists. I have seen as much as 4" drop difference at 300 yards in extremely cold temps, but I suspect it is a combination of cold powder, cold rifle, cold stock, etc, not powder alone. Lot-to-lot variations often exceed temperature differences. Testing ammo that has been chilled is not a realistic test, since the firearm should also be as cold to see the real picture. Hodgdon has made a deal out of their extreme line of powders, but I observe differences with it as well in real cold weather. I have hunted when it was -40ºC outside, and the firearm gets mighty cold in a very short time if you are wandering around at those temps!! I would never choose a powder for "hunting" basing my choice on temperature sensitivity alone. If a powder performs well all through the temps that I might be afield, I will use it, even if I lose 100fps or a bit more in the cold. For long range match shooting, I may choose the least sensitive powder if I expect temperature variations of some magnitude during the day. Regards, Eagleye.
 
I have not noticed much difference with my hunting rifles but, in my 300 win with RL-22 from winter to summer its safe to add 35-50 fps as the tem goes up same as my 308 tactical and target rifles with RL-15 that is the reason i switched powders because load development gets bounce around.

I moved to the Hodgdon brands for target shooting.

As for hunting out to 300 yards I would not worry for the most part grouping was good it was the POI was getting messed on my for my clicks.

I would only worry if you develop a supper hot load in the winter and shoot in the summer

These are my own findings maybe someone seen it different
 
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