Vertical bullet stringing

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by sewwhat89, Aug 21, 2005.

  1. sewwhat89

    sewwhat89 Well-Known Member

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    What causes bullets to string vertically, inconsistent meplats or velocity variations? I shot a group at 500 m and the bullets are within a quarter inch horizontally, but vary 4 inches vertically. Any suggestions?
     
  2. 11B2CV

    11B2CV Member

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    Your breathing! /ubbthreads/images/graemlins/grin.gif
     

  3. 7Rumloader

    7Rumloader Well-Known Member

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    Velocity variations will definitly cause it and I would think the inconsistent meplats would too. I would check velocities and get the load with the smallest spread for long distance work.
     
  4. sewwhat89

    sewwhat89 Well-Known Member

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    I am shooting 175 gr SMK in 300 SAUM. The bullet's meplate seem to vary greatly to the naked eye. The load I am shooting varies from 2946 to 2954 at 15 ft. I have shot it several times, and in the East Tx humidity and heat the loads have always shot the same. I shoot the 500 m targets early am to avoid the wind and mirage, but the bullets ALWAYS string vertically on me. These do at least. The 150 AB always put two touching then one flier, so I shoot the SMK. I never (knock on wood) have fliers with the SMK out to 300 yds, but at 500 the group goes vertical.
     
  5. 1doug

    1doug Well-Known Member

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  6. royinidaho

    royinidaho Writers Guild

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    [ QUOTE ]
    I am shooting 175 gr SMK in 300 SAUM. The bullet's meplate seem to vary greatly to the naked eye. <font color="blue">500 yds is most probably too close for meplates to make that much difference. </font> The load I am shooting varies from 2946 to 2954 at 15 ft. <font color="blue">That seems pretty good so shouldn't be a problem </font> I have shot it several times, and in the East Tx humidity and heat the loads have always shot the same. I shoot the 500 m targets early am to avoid the wind and mirage, but the bullets ALWAYS string vertically on me. These do at least. The 150 AB always put two touching then one flier, so I shoot the SMK. <font color="blue">Is this ALWAYS the case. How far away is the flyer? </font> I never (knock on wood) have fliers with the SMK out to 300 yds, but at 500 the group goes vertical.

    [/ QUOTE ]

    <font color="blue">What is the symetry of your SMK groups at 300yds? If there is no vertical stringing @ 300 there should be no stringing @ 500. If your groups are good @ 300 and vertically sting @ 500 the first thing I'd check is the parallax. What are your scope details? AO adjustment etc? If an AO then make sure you adjust from 300 to 500.

    Next I'd check the front rest. If too hard vertical stringing can occur. If its a pedestal rest and sandbag make sure the stock doesn't stick to it. Should slide easily. Also make sure that the sling thing is not recoiling back into the sand bag. That'll drive ya nuts plus mess up the stock sooner or later. </font>
     
  7. sewwhat89

    sewwhat89 Well-Known Member

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    The scope is a Zeiss 4-14x44. The gun slides in the rest, but the swivel stud does whack the bag pretty good. It has a nice channel gouged in it.

    At 300 yds, the SMK dont really group well, and the AB put 2 touching and the other about 3 inches away up and left. Every group fired has done that. Its either the first or last shot that is the flier. The SMK group 0.25" at 100, 2" at 200m, 3.5" at 300 yd, and 4.2" at 500 m. I am beginning to think I am the problem. I have limited experience shooting "long" range, and it is a new gun.
     
  8. jb1000br

    jb1000br Well-Known Member

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    I would definately read the vertical article linked above. If the gun will move at least 1/2" before whacking the sling stud then you can eliminate that as a problem.

    It would take a LOT of velocity variation to string them like you say!

    forget meplats until you can keep vertical under 2" at 500M

    I would let someone else shoot a group under similar conditions and see if they get the same stringing.

    JB
     
  9. sewwhat89

    sewwhat89 Well-Known Member

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    I'll get my little brother to shoot it. He shot my .22-250 under 4 inches at the same range with the mirage, etc. If he keeps it tight, I'll go over each step in that list on 6br site and see what I can do.

    I am also going to try the 178 gr AMAX and see if it makes any difference. In my .22-250 the 52 gr AMAX shoots 4050 fps out of my 26" barrel, and the 52 gr SMK shoot 3740 fps with the same load under the same conditions. Maybe in my SAUM I will get the same/similar boost in velocity. Neither load in the .22-250 show signs of excess pressure, but the AMAX copper foul my barrel like crazy. But at 4k+ what can I expect?
     
  10. 7Rumloader

    7Rumloader Well-Known Member

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    [ QUOTE ]
    The load I am shooting varies from 2946 to 2954

    [/ QUOTE ] Thats not much variation.
    Do like jb and others said let someone else shoot a group and check their results. Then eliminate as many of the things from the 6br site as you can until you get your vertical down.
     
  11. jb1000br

    jb1000br Well-Known Member

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    Brother if you have 4000+rds thru that 22-250 you need to rebarrel!...this may explain the problem /ubbthreads/images/graemlins/wink.gif

    JB
     
  12. sewwhat89

    sewwhat89 Well-Known Member

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    [ QUOTE ]
    It would take a LOT of velocity variation to string them like you say!

    forget meplats until you can keep vertical under 2" at 500M

    JB

    [/ QUOTE ]

    Shot again this weekend with the 178 gr AMAX. Put all four rounds into a 2.5" ctc group. The 175 SMK went into an 8 inch group. Using a different lot powder, the velocity was down to 2815 from 2950! The AMAX only needed 2 clicks more with the lower velocity to hit the mark.

    Thanks for all the tips! Now I just need more practice and to get the trigger under 5 lbs.
     
  13. Carbonman

    Carbonman Active Member

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    [ QUOTE ]
    The scope is a Zeiss 4-14x44. The gun slides in the rest, but the swivel stud does whack the bag pretty good. It has a nice channel gouged in it.
    At 300 yds, the SMK dont really group well, and the AB put 2 touching and the other about 3 inches away up and left. Every group fired has done that. Its either the first or last shot that is the flier. The SMK group 0.25" at 100, 2" at 200m, 3.5" at 300 yd, and 4.2" at 500 m. I am beginning to think I am the problem. I have limited experience shooting "long" range, and it is a new gun.

    [/ QUOTE ]

    Pull the swivel stud and I bet most of the vertical goes away.
     
  14. sewwhat89

    sewwhat89 Well-Known Member

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    I went through the site and "studied" up. Got the 175 smk into 1.7" outside-outside group at 535 yds (3 shot group). The 178 AMAX were about 2.2 inches. Its amazing what one seemingly insignificant flaw in your technique can cost you in terms of accuracy. Thanks guys! /ubbthreads/images/graemlins/grin.gif