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home Forums – The GUN Forum Ammunition Reloading Is there any truth to the statement “temperature has a very large impact of how hot a load burns. If a load was tested safe at 70F, it may not be safe at 100F.”

  • Is there any truth to the statement “temperature has a very large impact of how hot a load burns. If a load was tested safe at 70F, it may not be safe at 100F.”

    Posted by james on November 9, 2021 at 12:55 am

    This statement was made in a gun forum I check out and I was curious for what y’all’s thoughts are on this.

    james replied 9 months ago 2 Members · 22 Replies
  • 22 Replies
  • jbomb1119

    Guest
    November 9, 2021 at 12:55 am

    Really just depends on how temperature sensitive the powder is. Some are more sensitive than others. I don’t think it would keep me up at night if I shot reloads that did fine at 40 degrees and the next day I was planning on shooting the same loads when it was 70 or 80 degrees but then again maybe someday I’ll blow my hand off idk 🤷‍♂️ lol

  • LBRYcat

    Guest
    November 9, 2021 at 12:55 am

    This is anecdotal I guess but a few years ago I was doing some load development with H335 for .223. The same charges that cycled fine in the fall, would not cycle in February when it was cold AF and I had to bump the charge a bit to ensure proper function.

  • kf4zht

    Guest
    November 9, 2021 at 12:55 am

    I’ve not seen any powders that swing that bad to where it would be a safety issue, but certainly some will swing enough to affect velocity and performance. Not sure a company would release a powder that would swing pressure that hard under “normal human operating temps”. Maybe if you were loading on the ragged edge.

    For someone who is going to be hunting, particularly in cold weather it is good to test in at least simulated cold so you know your velocities

    If you really wanted to go down a rabbit hole you could look at the effects of cold on the metal of the firearm and if while the load pressure may be lower the change in metallurgy may make it basically the same risk factor

  • Sinky2086

    Guest
    November 9, 2021 at 12:55 am

    Tempature is a factor in how hot a load burns. To what extent, is highly powder specific. There is a lot of redneck science and actual science plus Fudd lore floating around this subject and I don’t know where to point you for any solid start for actual research.

    That said, if you are within published load data, I wouldn’t worry. You are far more likely to have group size issues than pressure issues using ammo that had its load development done in a different season.

  • HellaCheeseCurds

    Guest
    November 9, 2021 at 12:55 am

    Is there *any* truth to it? Probably.

    Should you or anyone be concerned about a safe load at 70° blowing up their gun at 100°? I’d say no.

  • ediotsavant

    Guest
    November 9, 2021 at 12:55 am

    This can be an issue if you are running max loads and developed them in cold weather. If you like to play on the edge then you should be using a temperature stable powder (e.g., Hodgeon Extreme powders) and developing your loads at the maximum temperatures you expect to shoot in.

  • Enough-Ad-9898

    Guest
    November 9, 2021 at 12:55 am

    If you’re not pushing max loads, or within 5%, it’s probably fine.

    Just be careful if you make a load for 20f and go to shoot in 120f

  • Thrall_babybear

    Guest
    November 9, 2021 at 12:55 am

    Complete Fuddlore.

    Temperature can affect velocity by a few hundred FPS in a rifle round. This is an accuracy issue at range, not enough to explode a rifle.

  • Sinky2086

    Guest
    November 9, 2021 at 12:55 am

    Tempature is a factor in how hot a load burns. To what extent, is highly powder specific. There is a lot of redneck science and actual science plus Fudd lore floating around this subject and I don’t know where to point you for any solid start for actual research.

    That said, if you are within published load data, I wouldn’t worry. You are far more likely to have group size issues than pressure issues using ammo that had its load development done in a different season.

  • BPCR_Abitibi

    Guest
    November 9, 2021 at 12:55 am

    I think temperatures problems depend on the powder used. I had problem in cold temperatures using published 357mag data with 2400 and regular SP primers. At -20°C, regular primers weren’t hot enough to properly ignite the powder and got a lot of unburnt powder granule and even a squib load. Since I mostly go to the range in winter time, I started using magnum primers for 2400 without any issues. As for other loads using W231, unique or trail boss, never had any problem at cold temperatures.

  • HollywoodSX

    Guest
    November 9, 2021 at 12:55 am

    Depending on the powder used, this can be 100% accurate or not very accurate at all. Some powders are designed and marketed as temperature stable (H4350 and Varget are famous for this), and some definitely are NOT temp stable.

  • CoRifleman

    Guest
    November 9, 2021 at 12:55 am

    IMR4350 for me is a great example of this. A max load at 40deg during elk season is noticeably hotter when doing load development in August and it’s 85.

  • BigBrassPair

    Guest
    November 9, 2021 at 12:55 am

    I have shot the same loads from low 30s to high 90s. Haven’t seen any pressure signs.

    Consider that the chamber of your firearm gets way hotter than that.

  • PXranger

    Guest
    November 9, 2021 at 12:55 am

    A 30 degree temp difference is not likely to be an issue, but double that, with a temperature sensitive powder, with a max pressure load at low temperature and you might have an issue.

  • ccatt327

    Guest
    November 9, 2021 at 12:55 am

    Safe is a relative term. My safe might not be someone else’s safe. I think first works loads up yourself or at least be part of the process to understand what the person producing it considers safe. Then I would look at the powder type both shape and powder. I have had better temp stability with extruded powders, but that’s not to say a ball powder couldnt out perform an extruded. If you made them or were part of the process and original testing then I would throw a chrono on the gun if there aren’t any crazy sores increases and the brass isn’t showing any signs well then…… if it seats it yeets!
    But honestly if there is ever a doubt not worth experimenting unless you understand the process, pressure signs, and what the rifle usually does with the round/powder combo. You can also use a program like quickload to get a safety estimate.
    Are you loading them, or is a guy your buddy knows?

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