500 yards and the weather?

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by diamondmfarms, Aug 16, 2009.

  1. diamondmfarms

    diamondmfarms Member

    Messages:
    19
    Joined:
    Mar 8, 2009
    Have a question everyone.
    Shooting 6mm .284 @ 500 yards with just under two inch groups. Last Sunday afternoon tempature was around 101 with indexs to 106. And the groups went out to four and half.
    My question is what effect does hotter temps have on ballistics?
    Or if someone has any info that would be of benifit to an old country boy send it on.
    Thanks everyone for the help
    God Speed Kendall
     
  2. britz

    britz Well-Known Member

    Messages:
    1,217
    Joined:
    Mar 11, 2007
    Weather has lots of effects on ballistics but I would say that the more likely culprits would be the chamber temp when you fired. or if you have a wood stock that was greatly affected by high humidity and high temps. or simply flinching/ misreading the wind.

    The terrain can affect longer shots quite a bit as well. Shooting over a valley will cause you to encounter much different wind patterns than shooting over a bean field. through clearings will obviously cause you to experience much different wind patterns as well.

    The cause of shooting a much poorer group isn't caused by ballistics as much as it is caused by inconsistency from firing to firing.

    Honestly, a 4" group at 500 is pretty darn good... it is pretty easy to misread wind at that range to get a bigger group --- or to flinch.
     

  3. diamondmfarms

    diamondmfarms Member

    Messages:
    19
    Joined:
    Mar 8, 2009
    Hey Thanks britz for the info ! ! !
     
  4. xdeano

    xdeano Well-Known Member

    Messages:
    165
    Joined:
    Jun 5, 2009
    The Temp has a huge affect on pressure and velocity. If your shooting that well before and it opened up I'd attribute that to powder. You may have a great load at 75 degrees but at 101 you might be pushing it outside the sweet spot of your rifle and making the group spread out. What kind of a group was it, round or directional? Any pics.

    xdeano
     
  5. diamondmfarms

    diamondmfarms Member

    Messages:
    19
    Joined:
    Mar 8, 2009
    morning xdeano

    using RL 22 45.7 105 Berger best group was 1.242 @ 500. I have pictures I just don't know how to put them on here. Have to put in some kind of URL or something.
    So do you think that at the higher temps the powder is burning faster? If so then I would need to load down for that.
    Thanks for all the info xdeano
     
  6. 260shooter

    260shooter Well-Known Member

    Messages:
    271
    Joined:
    Oct 16, 2004
    +1 on what xdeano said. RL-22 is very temp sensitive. Back off .5 to 1. gr and things should improve. when you do load work up, note as many conditions as you can. Also make notes when shooting in other conditions. If the load still shoots good in hotter or colder weather just use different drop charts. If it doesn't use a cool weather load and a hot weather load.

    260
     
  7. diamondmfarms

    diamondmfarms Member

    Messages:
    19
    Joined:
    Mar 8, 2009
    Thanks 260Shooter for the help and info.