Message to Shawn Carlock from DUH

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by Down Under Hunter, Jan 19, 2008.

  1. Down Under Hunter

    Down Under Hunter Well-Known Member

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    Shawn,

    You wanted me to keep you posted with how my new rifle is coming along. Well here is the latest from this afternoons session. distance is 1029 yards.

    Below is a 4 shot group with 300 smk from a DE 338 edge. Group was shot off harris bipod and rear bag.

    Conditions were

    Alt 569 ft

    BP 29.2

    RH 71.5

    Temp 77.5

    I got ready to go and pulled out the PDA and Kestrel. Guess what ? Flat battery on the PDA. So I think to myself fire a sighting shot and adjust for a group.

    I take a guess at the dope and dial 24 MOA up and fire. Keeping in mind I had never fired at a target anywhere near this far, but feel confident based on how I had been shooting. BOOOOOOm , whooosh Clang !!!! MAN !!! Holy smoke !! Straight into the circle centre mass.

    Three shots later this is what I had. See below...

    [​IMG]

    The 4 shots are the red ones !

    Group size from side to side from centre point of strikes is 3.75 " across and 3.5 " top to bottom.

    The first time I have ever shot at 1000 yards . Cant get the smerk off my face !!

    One question though. When I came home and fired the pda up and put all data in NF exbal came back with 26 moa up, not the 24 I dialed ? Can anyone suggest what I might need to do to get my actual drops agreeing with the PDA ? To get the moa to match I put 2930 fps instead of 2830 ??

    This post is to illustrate how good a class rifle can make an average marksman. Cheers to you Shawn.

    As I always say... God help the deer Down Under !!

    DUH
     
  2. dogdinger

    dogdinger Writers Guild

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    Wow...

    that is impressive.....cancel that offer to take you elk hunting......all we would be doin is packin your meat!!!!keep us posted when you stretch that to 1500......AJ
     

  3. royinidaho

    royinidaho Writers Guild

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    Very good.......... We have no funny face for a "smerk".:D

    I'd like to learn what you did to solve the 2 MOA difference.

    When I look at the globe I notice that gravity is actually pulling the bullet up for you down under fellas. I wonder if that makes a difference.:D
     
  4. wnroscoe

    wnroscoe Active Member

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    Good shooting. Check the sight height setting and rated BC. The BC in your program may be a little off from what you actually have. Also, make certain that you have a "HARD" 100 yard zero that your working off of.
     
  5. Shawn Carlock

    Shawn Carlock Sponsor

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    DUH,

    If i was making an educated guess I would say the pressure seems a little high. If it was off .5 or .6 to high this would cause the effect you are seeing. 29.2 is almost std sea level. Calc std at 569 ft is something like 28.8 in the conditions you gave. Assuming that you were shooting over flat ground with no wind over terrain features to cause this I would check the following:
    1. Your Kestrel's BAR Pres is referenced to 0' elevation giving you raw station pressure.
    2. You entered the reading into the pressure at altitude box and unchecked the calc std pressure box.
    3. The Exbal program seems to work very well with the 300 SMK and the BC it assigns it. I doubt there is an issue there. I'm fairly certain your not shooting 2900+ so that only leaves not getting the right info in the right location in the program or a shooting condition you just are not seeing.
    4. On conditions, were you flat? Was there even the slightest head or tail wind? Was it in the morning when the temp is rising. Did you have the Kestrel out in the conditions for a while for it to settle in?
    Don't you just love these guys that say long range hunting is the easy way out?

    Also glad you like the rifle. Pretty tough not to like a rifle that just about shoots itself.
     
  6. davewilson

    davewilson Well-Known Member

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    one thing to check is to make sure your scope is actually moving the 24 minutes that you adjusted for. maybe it actually moved 26.

    oh yeah, very nice shootin! it does give you a case of "smileitis" when you walk up to that first good group at distance. looks like another notch to go on the side of Shawn's lathe!
     
    Last edited: Jan 19, 2008
  7. Down Under Hunter

    Down Under Hunter Well-Known Member

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    Shawn,

    I'd say it probably would be my inexperience with the kestrel giving me the problems. The BP is the one I am unsure of. I have not calibrated the kestrel yet. I let it sit for around 5 min before reading it. I was shooting into a 4-5 mph 12 oclock head wind. Would I be better leaving the BP as STD pressue and putting the altitude in ? I'm sure I just need to tweak something a little ?

    I'd say the numbers would suggest around 2830 fps based on what it has been doing, but last time in the extreme heat I was shooting around the 2 moa high at 700M and high at a 415M target as well.

    I had a dead level reading on my aci as well ?

    Just got to learn how to drive that kestrel me thinks ??

    Cheers to all.

    DUH
     
    Last edited: Jan 19, 2008
  8. Shawn Carlock

    Shawn Carlock Sponsor

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    DUH,

    Two things to look at:
    1. Even though you are shooting level are there any ridges, slopes or draws between you and the target? If there are with a head wind these terrain features can cause a lift and make you shoot "flatter". If not then look at # 2.
    2. Take your Kestrel out and page to BAR Pressure, on most modles hold both buttons down and it will switch to a screen with elevation this is the elevation the pressure is referenced to, make sure it is at "0". Now your Kestrel thinks it is at sea level no matter what and gives you "raw" or station pressure. Enter this into your Kestrel in the pressure at altitude box and uncheck "calc std pressure" box. This should enter the correct pressure into Exbal.

    Also just in case check the basics:
    Check 100 yard zero.
    Check that click values are .25 moa.
    Check every single box in Exbal to ensure all data is correct.

    Hope this helps.
     
  9. Eaglet

    Eaglet Well-Known Member

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    DUH,

    Your problem is not a problem, you'll figure it out! Definately an awesome rifle though the shooter has his part on a group like that.
    Great shooting and congratulations on your rifle.;)
     
  10. Down Under Hunter

    Down Under Hunter Well-Known Member

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    Shawn,

    Yes I am shooting accross a draw that drops around 200 ft then rise to the target at about the same height as I shoot from. The heads of the trees in the draw I shoot accross are at around the 750 m mark. The breeze was good and steady hitting me on the nose straight on.

    I checked the kestrel and pressed the sequence of buttons and it showed zero with a blinking (ref ) , I quess that stands for reference. Tonite I get sittng at home 29.77 inHg ? My alt at my house is 140 ft currently.

    I checked the conditions from the previous shoot. I was firing from a different position at the same gong, but the distance was 700M. Guess what ? The wind was also solid 4-5 mph from 12 oclock. The shot travels over the same draw. Exbal came back with 16. 5 moa up. I ended up shooting 14 moa up in real bad mirage and landed the 3 shot cluster about 4 " dead centre high of the black circle. This really suggests that the shots travelling over the draw in a head wind most likely are getting around 2 moa lift ? Does that seem logical ?

    I also had a 415 gong out that day and shot across the same draw. exbal gave 7.5 up in the mirage. I ended up shooting 6.5 up and still was 10.5 " high of centre. Maybe a combination of mirage and lift ?

    The same day I fired at a 340 m target that is .99 cosine down hill with no draw to cross. Hit dead centre ?

    Maybe I should try and set up a long flat shot at 1000 and take the draw out of the equation to see if the pda agrees with the strikes. I would have thought that should conclusively tell me if the draw I'm firing across is causing the lift ?

    Shawn,

    What figure do you use in the scope height above bore. I put in 1.5 " ?? BC is .768

    Eaglet,

    It sure makes you strut around a little when you hit your first 1000 + target in the lungs.

    Cheers

    DUH
     
    Last edited: Jan 20, 2008
  11. Down Under Hunter

    Down Under Hunter Well-Known Member

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    AJ,

    I sure feel confident right now about drilling a big old six point that walked out of the timber in front of me. I will post a 1500 yard target as soon as I find a suitable place to test at that range.

    Around my area, its harder than it sounds.

    Cheers AJ..
    DUH
     
  12. Shawn Carlock

    Shawn Carlock Sponsor

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    DUH,

    Go to my article I have on reading the wind. You will find a diagram I drew describing what I believe is happening to you. With a head wind over the terrain features you describe you will get a lift from the wind blowing up the face of the draw closest to you. This effect is readable and correctable a certain amount (it still comes down to your best guess). In the diagram I have your exact shot (almost) based on your description. I would bet this whole issue is a wind over terrain thing. Two things, your scope height is probably 1.9-2.0", measure from center of barrel to center of scope to get this, also find some shots to shoot over flat terrainless ground. If your in canyon country it may be best to shoot down one side of the canyon to get away from the lifting effect.
     
  13. Down Under Hunter

    Down Under Hunter Well-Known Member

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    Thanks Shawn for your help. I'll let you know how it goes !

    DUH