Temp Stability?

[HappyGVM]

Hi Everyone,
I've read numerous posts indicating that a particular powder is temp sensitive while another isn't. In my case I'm using Reloader-22, a powder that IS temp sensitive, for a 300 Wby hunting load. I'm pushing 180 gr Scirocco 2's at an avg vel of 3213 fps that is dead on at 200 yds. I'm loading them here in Central TX where I'm lucky if its 80-85 degrees in my shop in the AM. When I zeroed it was about 88 deg. I've got a WY elk hunt planned for the 3rd week of Oct near Gillette where average daytime highs are 52 & lows are 30 degrees. I estimate the hunting area is about 6000 ft in elevation vs 545 dt here. Can anyone tell me what sort of impact the temp change will cause or what POI shift I can expect when I get up to WY.
Thanks for your Help!
Happy

 

[fruitnut]

The lower temperature will decrease the velocity causing the bullet to shot lower. But the higher elevation will cause the bullet to lose less velocity with distance. So, time of flight to reach 300 yards probably won't be much different. Meaning drop will be about the same.

I'd wait until you get there and try a shot at 200-300 yards and see where you're at. Out to 300 yards it probably won't matter. At 500 yards it might.

 

[Rick Richard]

Hi Everyone,
I've read numerous posts indicating that a particular powder is temp sensitive while another isn't. In my case I'm using Reloader-22, a powder that IS temp sensitive, for a 300 Wby hunting load. I'm pushing 180 gr Scirocco 2's at an avg vel of 3213 fps that is dead on at 200 yds. I'm loading them here in Central TX where I'm lucky if its 80-85 degrees in my shop in the AM. When I zeroed it was about 88 deg. I've got a WY elk hunt planned for the 3rd week of Oct near Gillette where average daytime highs are 52 & lows are 30 degrees. I estimate the hunting area is about 6000 ft in elevation vs 545 dt here. Can anyone tell me what sort of impact the temp change will cause or what POI shift I can expect when I get up to WY.
Thanks for your Help!
Happy

At most hunting distances your worrying for nothing since it so minimal. If you want to know, play around with a Ballistic program like the free one on the Berger website.

The only time I would worry is if you're loading at a very low temp and at max and then going to a hot temp. That could create pressure issues.

 

[fruitnut]

I played around with the JBM calculator. The difference in drop even at 500 yards was about two inches max.

At 500 yds 3213fps 90F and 500ft elv drop was 28.4 inches

At 500 yds 3113fps 50F at 6000ft elv drop was 29.6 inches

At 500 yds 3163 fps 50F at 6000ft drop was 28.2 inches

In other words, thinner air cancels out loss in muzzle velocity and drop to 500 yards is basically the same. All calculated at zero as close to 200 yards as I could get. Couldn't figure out how to set zero at 200. So used a vital zone radius of 2 inches which gave zero near 225 yds.

 

[just_jon]

According to QL, you will lose roughly 6,300 psi and 90 fps between 88 and 30 degrees. I suspect you will gain back enough of the lost velocity at 6000' that it will not be a factor at normal hunting distances.

Try chilling your ammo in an ice chest on your next range trip. This should give you an approximation of POI shift.

 

[RockyMtnMT]

All powders are temp sensitive to some degree. Some more than others. @Rick Richard is right on. The internet has a way of making way more out of temp sensitive powders than it actually is. At 2000y you will have to make adjustments every day and even every hour with every powder. I don't suspect you are shooting that far at game. Under 800y I don't suspect it will make enough diff to matter. Verify your zero when you get there. If you are shooting truly long range then confirm your drops at long range when you get there and adjust for the atmosphere at the time of the shot.

 

[HappyGVM]

Thanks a lot, Guys!
Cheers,
Jerry

 

[Wedgy]

Or keep you rounds/magazine inside your jacket until you are ready to shoot. What is the maximum range you would shoot take a shot at an elk ?
The temp here is in the 100's and test my rounds held in the fridge for a day then take them to the range in a cooler on ice and shot my elk at 1,058 yards in -5F in Wyoming and it worked just fine.

 

[Turpentine21]

Yes there can be drop. But also the lower temps may slow the load down enough to throw you out of the accuracy node which could induce an impact shift to the left or right. Likely not much but it is possible and likely doesn't matter much at shorter ranges. I would definitely shoot it when I got out there and re zero if necessary. Better safe than sorry.

 

[fmuguira]

As mentioned, shoot it when you get there. I be shot a lot of R22 over the years in my 300 WM and any changes were minimum and I harvested animals out to as far as 550 yds.

 

[MagnumManiac]

My only concern would be uphill/downhill shots being flatter at higher altitude. I ran into this exact problem and shot over the animal twice, the third shot taking him very high in the shoulder disabling him for the finisher. I was aiming at the lower chest, and could not see where the chest stopped due to the Tahr standing in tussock and was partially obscured on the back third.
This event had me re-thinking every uphill/downhill shot ever since, even bamboozled myself on a shot because I didn't use the golden rule "Aim at hair, not air" and the shot went exactly where I was aiming, below the brisket into the ground…
Edit to add: My rangefinder was not adjusted for the elevation, it was still on my home parameters in Australia, not for New Zealand…

Cheers.

 

[scdogman]

If load development is done in cooler temps, then shot in the summer, you could see dangerous swings. Not the case here, but some have locked up their bolt.

I shoot at 95 to 100 degrees and will hunt at 10 to 20. I did see -9 one year, so 100 degrees swing is possible for me.

I'm more concerned with getting out of the accuracy node by losing speed. I would put rounds in an ice chest and chrono the difference.

If there was significant, i would keep bullets warm until i plan to shoot.

A range finder and a cheap/free ballistic solver solves aim point issues.

 

[HappyGVM]

Thanks for the info and insights!

 

[thatguyshm]

I use RL22 often. In my 30-06 there isn't a better powder for 180 class bullets.

When I do summer load development, I'll toss some ammo in the freezer over night then take it straight to the range and shoot it for accuracy.

It's one more check I do only with my hunting ammo. With 30-06 ammo, it's never been enough to worry about the loss in accuracy from other powders.