How Hot Is To Hot To Work Up A Hunting Load?

[highside74]

I would like to get a load done for my 6.5PRC. I have all the components but was concerned summer weather might not be the best time to work up a load that will be used in Oct. and Nov. 

My scope is a vx6 but I'm still using the factory dial. If I have a load worked up now will it be just as accurate in the fall? Will I just need to re chrono it during cooler weather? What would you guys do?

[hogslayer]

If you use temp stable powder it will.  Just shoot in the morning and evening.  During the day, heat and mirage will throw you off.  Mornings are usually less windy.  H1000, N565, H4831sc, RL23 would be my choices.

[buckfvr]

I do my testing as early in the morning as I can.  Your ballistic app has temperature input so be sure to do that.  For hunting I run cheat sheets laminated and attached to my range finder.  I go with at least 2 settings for both elevation and temperature locally.  You can do the same for conditions you intend to hunt out of state.  If in doubt, just range and pull up your ballistic app and enter current conditions.  I find this too time consuming so hence the small laminated cheat sheet/cards on my range finder, which by the way work perfectly.

[CaNINE]

I always put my ammo on ice even with temp stable powder just to ensure I’m testing with ammo at hunting temps. But I’m OCD when it comes to reloading and testing.

If you do this it doesn’t matter what the ambient temp is. Just don’t let your rounds cook to long in the chamber and let the barrel cool down to ambient every 3 shots or so depending upon load.

[Fidelk]

In the past, I had been told to only sight in a rifle during cooler days to approximate conditions found during the cooler hunting seasons. I don't reload but the guy telling me this was a serious handloader. I mentioned this to my hunting buddy since we will be hunting in warmer weather this year......and we have cool weather zeros on our rifles. He's an engineer, so he deep dives into these scenarios. His response:

"I played around a bit with the Winchester ballistics calculator, which allows air temperature input, and the effect of a 40 degree increase from 60 F to 100 F is miniscule.

If I'm shooting my .300 WSM at a target 500 yards downrange, there is a 25.0" drop at 60 F.

At 100 F, the drop is 24.4", which is less but only by 0.6". Like I said, miniscule."

[buckfvr]

And then theres elevation to consider.

[Magnum_Willys]

Shoot early temps in 50’s.   I use a 12v mattress pump with a piece of surgical tubing for barrel cooler.  Triple output of commercial barrel cooler units - tho noisy

[GWP]

My experience is also that there is not enough difference to worry about.
Two of the best shooters I have known could probably out shoot me laying upside down, head down on a hill, with Wasps hovering around their head regardless of ammo temp.
Also, it really depends on the rifle.
I have two that air temp does not matter, and one of them I have put 14 non stop shots, 1 min between shots, with no change in impact. I had another that air temps would make it do weird things.
Take some rounds and put them on ice and put others in your pocket, take them out and start shooting. See for yourself what you find.

[Sliverslinger]

And then theres elevation to consider.

I would argue that for 500-1,000, this is more important than temperature. This assume you’re not leaving your ammo laying out in the full sun on a hot day or something crazy.

[Mulie87]

Work up a load and you’ll be fine. Just make sure you confirm zero before you hunt. I zero’d my .300RUM in western wa at 800ft elevation and went hunting in SE MT at 3,200ft. I shot a doe at 720yds right on the shoulder. You’ll be fine! I too print my data and tape it to my scope. I use the Hornady 4DOF ballistic calculator and it serves me well. The week I leave to hunt I look at the forecasted weather conditions where I’m going. I input the environmental factors in the calculator, and print a chart 200-1000yds in 50yd increments. Print, tape to scope and go hunting. Hope this helps.

[Alan K]

Mirage is more of a problem judging group sizes and being sure it was the load rather than the heat waves.  Always shoot first thing during summer months and been fine.

[Mulie87]

  mirage is a killer. I agree, shoot early in the morning during warmer months.

[hunter399]

Sight in today ,hunt bear in August.
I always check my zero before season.
So around Oct I will check my zero again.
Work up a load ,don't worry about the weather.
Check your zero before season and go.