accuracy changing with temperature?

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by ncharter, Feb 2, 2004.

Help Support Long Range Hunting by donating:

  1. ncharter

    ncharter Member

    Nov 15, 2003
    Sorry guys but I have a totally newbie question here. I have been doing load development for my recently purchased 300RUM for the last two months and have had great sucess(for my standards at least)finding several loads that are below 0.5MOA and one that is consistently at 1/4MOA. I am using Reloader 25 as the powder for all loads. The only thing that I am worried about is the fact that all of my shooting has been done in temps between 15 and 25 degrees. I have seen other posts wherein people stated that the loads they developed in the winter did not shoot well in the warmer months. If this is indeed the case is it due to increased velocity/pressure? Would I be able to remedy the problem by lowering the powder charge until I acheive the same average velocity that I got during development. Any information would be greatly appreciated.
  2. LDO

    LDO Well-Known Member

    Sep 23, 2003
    you got it right,if in warmer months you see pressures just play with the powder a little and you should be right back on track-my-2-dave
  3. Brent

    Brent Well-Known Member

    Jun 12, 2001
    I think you're on the right track. I would look for the MV range it shoots well within and the upper end in the heat would be my target. Your best indication of changes in chamber pressure is your MV.
  4. Mysticplayer

    Mysticplayer Well-Known Member

    Jul 27, 2001
    labrat, have a RUM and was using H870. Shooting during our super hot summer was an adventure. Yes, changes is temp can have dramatic effects on pressures and pressure curves/barrel harmonics.

    That is why I use h50BMG during the warmer months now. It is supposed to be temp insensitive and the other powders in the Extreme line seem to work very well from freezing to toasty summer heat. The h50BMG shoots better too.

    If you like the Re25, just adjust as necessary as the temps warm up. It should still work fine.