cold weather load workup

[alaskan9974]

Relatively new to reloading. I finally have had time to work up some loads for my rifle, found the nodes will be working on seating depth next.

Wondering if there is a rule of thumb on when it is necessary based on temps to check on load pressures?

 

[Darkker]

Unless you have a notoriously old-tech powder, then normal rules apply:

-There is a VERY real reason why the warnings on powder warn that lots can vary by 10%
- If you ever meet book max velocity, you are over pressure, REGARDLESS of charge weight, back to the first warning.
-Extreme powders aren't a universal, magical thing. So don't ignore the first two if you use them.
-Verify velocities when temps get above 85-90°

 

[alaskan9974]

Thanks, I am using Retumbo in my Lapua, right now I have a wide node 95.5-96.3 with a 250 SMK. The temps both times I have been out have been around -20f so I will put some together at a smaller charge for when temps come up in spring. Our flat light plays havoc on my two chrono's, so all I have is drop data.

Unless you have a notoriously old-tech powder, then normal rules apply:

-There is a VERY real reason why the warnings on powder warn that lots can vary by 10%
- If you ever meet book max velocity, you are over pressure, REGARDLESS of charge weight, back to the first warning.
-Extreme powders aren't a universal, magical thing. So don't ignore the first two if you use them.
-Verify velocities when temps get above 85-90°

 

[Lefty7mmstw]

Up here in N.D. I always build my loads based on both cold and warm weather performance. It takes a bit of time but you'll find out rather quickly what should work in your rifle for both.
I am not really a Hodgdon fan (more into rl powder) but I do burn a bit of retumbo and keep a keg in the basement. It will be a decent powder for all temps with your Lapua; my brother is using retumbo in his Lapua too. I would always keep a few % headroom and never run it to the sticky bolt point. A bit milder load usually shoots lower average group size and is easier on your barrel too. I'd use a wlrm or 215 to fire that much powder in cold temps too...

 

[alaskan9974]

Up here in N.D. I always build my loads based on both cold and warm weather performance. It takes a bit of time but you'll find out rather quickly what should work in your rifle for both.
I am not really a Hodgdon fan (more into rl powder) but I do burn a bit of retumbo and keep a keg in the basement. It will be a decent powder for all temps with your Lapua; my brother is using retumbo in his Lapua too. I would always keep a few % headroom and never run it to the sticky bolt point. A bit milder load usually shoots lower average group size and is easier on your barrel too. I'd use a wlrm or 215 to fire that much powder in cold temps too...

Thanks, I am using WLRM primers. No issues lighting off in -25f. Went out and lit off a few rounds at -35f just for kicks and it worked fine after acclimitizing for a few hours before firing. Just wanted to check functionality.

Is Retumbo the best powder for large temp swings? I have H1000 and 780 and 869 available as well to purchase. Just wanted to check before I bring some more retumbo home.

 

[Lefty7mmstw]

Thanks, I am using WLRM primers. No issues lighting off in -25f. Went out and lit off a few rounds at -35f just for kicks and it worked fine after acclimitizing for a few hours before firing. Just wanted to check functionality.

Is Retumbo the best powder for large temp swings? I have H1000 and 780 and 869 available as well to purchase. Just wanted to check before I bring some more retumbo home.

Retumbo is decent, but the powder isn't the only variable. barrel dimensions change (very slightly) and primer temp can change too. not to mention the shooter is part of the velocity equation and more clothes let the rifle push back a bit more loosing a bit of velocity...

 

[Laelkhunter]

[ to mention the shooter is part of the velocity equation and more clothes let the rifle push back a bit more loosing a bit of velocity...[/QUOTE]

Lefty, not doubting you, but I have never heard that the bullet would lose velocity because of the rifle's recoil or rearward movement.. Interesting theory. Has anyone ever tested it ?

 

[Lefty7mmstw]

[ to mention the shooter is part of the velocity equation and more clothes let the rifle push back a bit more loosing a bit of velocity...

Lefty, not doubting you, but I have never heard that the bullet would lose velocity because of the rifle's recoil or rearward movement.. Interesting theory. Has anyone ever tested it ?[/QUOTE]
I know Kevin Thomas from lapua usa has spoken on rifle performance variations, but at a glance I can't find the thread. I do know there is enough difference just in grip variance with an autoloader for a loose grip to cause cycling malfunctions in some designs. I'm not going to shiver in sub zero weather to try the theory on rifle velocity though... I might possibly don a coat in the summer; stay tuned though as it's around zero here at present...

 

[Capt RB]

Hodgdon list the 250 Hornady max load for a 3.550 coal at 98 grains compressed. The only Serria load is for the 300 grain bullet at 94 grains. Once it warms up to summer temps restart your loading at the low end. Another way is to shoot to a warm barrel and leave the round in the chamber for a few minutes or keep the rounds inside and go from room temps to warm chamber and look for pressure signs. You should be well within safe parameters however your face is sitting directly behind the only protection you have.lightbulb

 

[Laelkhunter]

Lefty, not doubting you, but I have never heard that the bullet would lose velocity because of the rifle's recoil or rearward movement.. Interesting theory. Has anyone ever tested it ?

I know Kevin Thomas from lapua usa has spoken on rifle performance variations, but at a glance I can't find the thread. I do know there is enough difference just in grip variance with an autoloader for a loose grip to cause cycling malfunctions in some designs. I'm not going to shiver in sub zero weather to try the theory on rifle velocity though... I might possibly don a coat in the summer; stay tuned though as it's around zero here at present...[/QUOTE]

Gotcha !! It's going to get cold and nasty here in South Louisiana soon too. Not planning on going to the range though. Let us know if you can. Thanks

 

[toddc]

Physics dictate that anything that recoils differently will have a different velocity. Is it enough to MATTER or even MEASURE? IDK I would GUESS the difference would be small enough to fall within ES and might be difficult to prove without averaging a large number of shots which in itself would be problematic due to the number of variables.
How the rifle is HELD will have a large effect so even if the velocity difference is small, the affect of the extra clothes could be significant.

 

[AZShooter]

I KNOW my lightweight 20 gauge autoloader occasionally won't cycle properly if held loosely but velocity changes with tight or loose hold with a rifle? Hard to believe....

To test the theory perhaps someone who owns a lead sled could put 100 lbs of weight in it and chronograph 25 rounds then do same off bags. NOW that would be an interesting test.