Home Forums Reloading Big Game Rifles Temp Sensitivity

Being really new to all of this. How much attention do I need to pay to the way the temp affects the different powders? Currently I have IMR 4350 and Varget on hand.

I shoot in the summer and early fall months, mostly. with temps being anywhere from 55-85* F.

Hunting seasons will be anywhere from probably -5 to 60'ish. Both of those extremes are rare. Most of the time it's 20-40 degrees during deer season.

Been using IMR 4350 in some of my hunting rifles and haven't noticed any need for concern when it comes to temp sensibility. Develop a load in summer and shoots fine in the cold.

Varget should be one of the best. If it worries you switch to H4350 or IMR4451 from IMR4350 (if you can locate them).

IMR4350 is temp sensitive. It was the first powder I ever tested after learning about the whole variability of powders in different temperatures. Now that was back in the 80's when (I think) Dupont still owned IMR.

Other than different velocity dependent on temps, the biggest concern is loading a max load in moderate temps and then shooting the firearm in hot weather--pressures can and probably will increase with temp sensitive powder. How much depends on particular loads, the actual temp of the ammo, and the firearm itself.


Casey

It seems a lot of the powders being introduced recently are more temp insensitive. I believe all the Hodgdon's 4 digit powders are temp insensitive. I've shot a LOT of different loads with H4831 and have found it to be very temp insensitive. The new IMR powders are claimed to be temp insensitive and I will probably be testing IMR 7977 in the future to find out.


Casey

It seems a lot of the powders being introduced recently are more temp insensitive. I believe all the Hodgdon's 4 digit powders are temp insensitive. I've shot a LOT of different loads with H4831 and have found it to be very temp insensitive. The new IMR powders are claimed to be temp insensitive and I will probably be testing IMR 7977 in the future to find out.


Casey

tzone

For our deer hunting in the woods I do my final site in at the temps and distance we experience hunting. What you are mainly looking for is a point of impact change, the loss of velocity will not matter at woods ranges.

I spoke with an Alliant powder tech a while back in reference to RL19. I was told to expect 1-2 fps per degree change, in my case this would be a loss of approx 90 to 100 fps in mv. I live in East Texas where temperature can and does bump 100 degrees. I will be hunting in Montana this Oct/Nov and temperature could be in 20s. A suggestion was to do what is above post! Resight the rifle at hunting site when temperature is much lower. POI is more important than a loss of mv at most shot distances of 300 yds or less.

I usually do a final "sight in" in late October just to make sure things are right. So I guess I'll be able to tell then.

I have quit loading IMR powders, sadly. 4350 was my go to but its been replaced on my bench by RL powders.
I had a good little load for the .270 (I thought anyway) which turned out to be very weak in low temps, which is when I hunt here in SD.
If I wake up and its zero or lower, I don't want to wonder what my ballistics are out in the field where it matters.