Node shift due to temp?

[savages]

Will the outside temperature and ammo temp change the harmonics and cause node shift?
Example: 20F to 90F outside temp?

I know that the POI will shift vertically due to the FPS change.

Curious because its 22F outside and I'd like to go work up some .243 95gr VLDs and .308 168gr AMAX loads.
Would hate to have spent the time and components only to find out that the loads open up significantly during the summer months.

 

[varmint slayer]

The powder temperature is what may change your POI. If you are not using an extreme powder like Varget, H4350 or any of the extreme powders from Hogdgon, then chances are if you develop a load in 20 degrees and go to shoot it in 90 degrees you may run into pressure issues which will change velocity and more than likely POI. Use an extreme powder and stay a grain or two off max load and you should be safe with regards to over pressure. You may still have to tweak your load come warm weather but at least your face won't get blown off if you don't use an extreme powder and stay 1-2 grains below max.

 

[Win_94]

I agree with varmint slayer. Using Hodgdon Extreme Powders, I see a loss of precision with most loads developed in summer that are shot in winter, and visa-verse. But not always, I have a 30-30 Varget load that shoots sub-moa from 10º to 95ºF. You'll just need to experiment.

 

[Sniper Uncle]

One old timer that I read from said that he single fed his rifle, keeping the loaded rounds in his inner pocket. This way, the rounds were at or near 70 degrees until place in the rifle to shoot. This way, you could probably work the load up pretty accurately, even with the cold weather. He also place some in a ziploc bag in a cooler of ice to test the effects of the cold on the same rounds. Just a thought....

 

[savages]

So if I work up loads at a cooler temp and find a powder charge that horizontally groups the best, that will change do to temperature induced pressure increase?

The 243 VLD load is using H414.
The 308 AMAX loads are CFE223 and Varget.
So the only one that will be remotely close will be Varget.

Looks like I've got a bit of load testing in my future.

 

[BGE541]

Are you familiar with the purpose behind OCW load dev? This is why a good powder as mentioned but also finding that node counts, so that if you get some (FPS) shift either way you will be ok. I wouldnt hesitate to find a great load at that low temp regardless... DOPE is DOPE.

 

[savages]

Think I found it.

http://optimalchargeweight.embarqspace.com/#/ocw-instructions/4529817134

Time to kick back for the evening and see what I can learn.

Thanks for the Romans 12:1 reminder. I needed that reminder, especially with all the rampant corruption that we are onslaught-ed with daily.

 

[427Cobra]

I found the with H4350 my 260 had no spread between 30-105 degrees outside, "extreme" is an understatement.