What is the real BC of the 240MK?

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by HoytemanPA, Nov 6, 2005.

  1. HoytemanPA

    HoytemanPA Well-Known Member

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    I was trying out my new barrel today and I'd like to know if anyone else has found the BC of .711 for the 240MK to be a bit too low?

    Thanks,
    Shummy
     
  2. jb1000br

    jb1000br Well-Known Member

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    Shum -- DC found the same thing! BTW -- check out my sigline...DC hangs out there and can give you the number he found when he gets back from killin stuff in CO /ubbthreads/images/graemlins/laugh.gif

    JB
     

  3. Jon A

    Jon A Well-Known Member

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    I recently measured it (velocity drop over 200 yds, corrected for conditions) at .635 from a 1:10 twist at a relatively low velocity (2850). I'm hopeful it'll measure a good shot higher when I re-measure from my 1:9 twist at a higher velocity (when I get my new barrel installed).
     
  4. HoytemanPA

    HoytemanPA Well-Known Member

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    My bad I found the error. I made a last minute 2 click zero adjustment and set my turret before going out to 400....adjusted the wrong way! Result was 1 moa that I couldn't crunch numbers for nohow. For a day I had a 3 MOA to 400 gun. Rechecked at 100 today and now its just a plain old 4 to 400 /ubbthreads/images/graemlins/grin.gif 3150 to 3200 is where it likes it so far. (Chrony numbers) The .711 should get me in the ballpark. Will know more when I go on out farther. Was going to test 800 and 1100 today but a big storm came in.

    Thanks for the info guys and I'll let you know what I figure out once I get a few more drop points and access to a 43.

    JB you going to the shoot Sunday?
    Shummy
     
  5. bailey1474

    bailey1474 <strong>SPONSOR</strong>

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    [ QUOTE ]
    3150 to 3200 is where it likes it so far.

    [/ QUOTE ]

    What are you shooting it in to get those velocities?
     
  6. HoytemanPA

    HoytemanPA Well-Known Member

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    Hi Bill,
    29 inch 30-378, throated so the boattail junction is just above the neck/shoulder, crammed .005, H50BMG 107.5 3130, 109.5 3170, 111 3220 (slight marks) Marks aren't as bad as some factory ammo I shot when it was a regular Accumark. Retumbo starts showing marks at 103 3185.

    I had just enough time to launch 3 of the H50 107.5's (3130) at 500 tonight. Had some mirage (riverbottom flat) but I usually do not get much wind affect vertical here. Although I was seeing at least an inch vertical jump of the bull due to the mirage, I was pleasently surprised with a 1.8 inch three shot, one of which was a fouled/cold bore. Scope was doped for 6.5 MOA and POI center was 1 1/4 inch high, 2 inches left. I did see the left push too but held center to see how much these big bullets would push.

    Needless to say I'm quite pleased with this inherently inaccurate Weatherby.
     
  7. Buffalobob

    Buffalobob Writers Guild

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    Shummy

    Is this gun on a Wby Mark V action?
    What make of barrel?
     
  8. CAM

    CAM Well-Known Member

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    HoytemanPA
    I knew sooner or later you would rebarrel or start over, LOL
    what twist and make is the barrel? 3 or 4 groove?
    I've never even picked up my accumark after receiving the custom!
    keep us posted
    CAM
     
  9. HoytemanPA

    HoytemanPA Well-Known Member

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    BuffaloBob,
    Yep, Mark V started out life as an Accumark. A couple of years ago it earned a Tooley MBR stock. Had a blast with it but wanted a bit more weight and barrel mass. Hart Long Heavy Varmint installed now. 16.1 pounds total with a 8.5 LRT.

    Cam,
    Its a boring 6 groove 10 twist. Same barrel as I have on my 300 Wby, which happened to print a carbon copy (1.77)three shot group at 500 tonight. It took 9 MOA to do it though with 220 MK's.

    I probably would still be shooting the Accumark barrel if I didn't have an itch to run the Wby action at a match or two next year. A couple of things were against it. It liked the 200 Accubonds best and while it was a 3 or 4 shot clay busting, chuck smacking SOB, the accumark contour couldn't take the heat required for 10 shot matches. About 7 shots and groups start to open and after making up my mind to rebarrel I found that 23 made things very, very bad.

    Will let you know what I come up with at 1100 later this week.

    Shummy,
    HoytemanPA (Back in my 3D bow days)
     
  10. HoytemanPA

    HoytemanPA Well-Known Member

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    24.5 MOA to 1100. (15mph wind from 10oclock, 3150fps, 40 degF) Kept dropping BC in Exbal until it lined out with my 500 and 1100 as shot and came up with .640 for the BC. Verified what JonA was telling me all along.