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Vertical stringing shots?

  • 03-06-2021 6:37am
    #1
    Registered Users Posts: 6,758 ✭✭✭ clivej


    At last my new CZ 457 LRP .22lr has settled down and is shooting good groups.

    I'm now getting consistent good groups of a one big hole of about 12mm/15mm ish @50m.
    BUT sometimes I'm getting vertical stringing in a 10 shot group of about 20mm.

    What causes this? Is it me, or something else that's happening?
    I'm shooting off the bench, with a good front rest and SEB back bag, the rifle is well supported.


Comments

  • Registered Users Posts: 1,025 ✭✭✭ Richard308


    It’s still respectable with a 22lr. Is it the start of shooting or after barrel has warmed up?


  • Registered Users Posts: 6,758 ✭✭✭ clivej


    Richard308 wrote: »
    It’s still respectable with a 22lr. Is it the start of shooting or after barrel has warmed up?

    It's well into a session, and could go from the sort of normal groupings to a string.


  • Registered Users Posts: 310 ✭✭ no_4


    What ammo are you using?
    clivej wrote: »
    At last my new CZ 457 LRP has settled down and is shooting good groups.

    I'm now getting consistent good groups of a one big hole of about 12mm/15mm ish @50m.
    BUT sometimes I'm getting vertical stringing in a 10 shot group of about 20mm.

    What causes this? Is it me, or something else that's happening?
    I'm shooting off the bench, with a good front rest and SEB back bag, the rifle is well supported.


  • Registered Users Posts: 431 ✭✭ badaj0z


    The main cause of vertical stringing is inconsistent shoulder pressure. If you have a light pressure the rifle will move back more in recoil. If you have a harder shoulder pressure, the rifle cannot move back as much, the energy has to go somewhere so the muzzle lifts. Inconsistent pressure changes the point of impact in a vertical direction. Check out turning moments in your school physics books (or your kids).


  • Registered Users Posts: 1,025 ✭✭✭ Richard308


    clivej wrote: »
    It's well into a session, and could go from the sort of normal groupings to a string.

    Hot barrel causes bullet climb. Where as a warm (sun kissed bullet) bullet improves accuracy.

    https://www.snipershide.com/shooting/threads/cold-to-warm-barrel-poi-shift-what-is-considered-normal-acceptable.213279/


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  • Moderators, Sports Moderators Posts: 27,534 Mod ✭✭✭✭ Cass


    Unless you have a chrono its hard to eliminate significant changes in bullet velocity as a cause.

    Forum Charter - Useful Information - RFDs - Ranges by County - Hunting Laws/Important threads


    If you see a problem post use the report post function, "FLAG" & let a Moderator deal with it.


    Your Shooting Forum Moderators - Cass, Cookimonster, Vegeta, Sparks, It wasn't me!



  • Closed Accounts Posts: 259 ✭✭ Bog Trotter99


    Richard308 wrote: »
    Hot barrel causes bullet climb. Where as a warm (sun kissed bullet) bullet improves accuracy.

    https://www.snipershide.com/shooting/threads/cold-to-warm-barrel-poi-shift-what-is-considered-normal-acceptable.213279/

    Another internet myth apparently.

    And when you think about it. The time a bullet spends in the barrel it would need to be some quite significant alteration to affect the bullet.

    Of course there is hot and 'hot'. Meaning if it gets too hot then other things may happen. But just hot after say 20 continuous rounds. No significant change at all.

    https://www.youtube.com/watch?v=xLOmWC_NfdA

    https://www.youtube.com/watch?v=QfNE1T6EWEk


  • Registered Users Posts: 310 ✭✭ no_4


    Could be, but I doubt it, no recoil from a 22 , my guess is inconsistent ammo powder loads
    badaj0z wrote: »
    The main cause of vertical stringing is inconsistent shoulder pressure. If you have a light pressure the rifle will move back more in recoil. If you have a harder shoulder pressure, the rifle cannot move back as much, the energy has to go somewhere so the muzzle lifts. Inconsistent pressure changes the point of impact in a vertical direction. Check out turning moments in your school physics books (or your kids).


  • Moderators, Sports Moderators Posts: 27,534 Mod ✭✭✭✭ Cass


    This feels like telling your Granny how to suck eggs. :D

    What position have you the rear bag and front rest in? Your rifle has a heavy barrel and while probably not as heavy as others a heavy barreled rifle will want to "tip forward". I had this with my BR rifle but she was over 13lbs. IOW as heavy as my FTR rifle.

    If I had the front rest to far back (towards the trigger) the "tipping point" of the rifle would be moved and unless I kept identical cheek pressure (which is very hard to do) on the stock she would give me vertical strings. Now I shot mine free recoil so this amplified the effect.

    My solution was to have the front rest as far forward (towards the muzzle) as I could and the rear back in the "sweet spot" to make sure the rifle was completely anchored. IOW its centre of mass was between both rests and not favouring forward or rear "tipping".

    Another tip is to make sure the butt stock is well placed in the rear bag. Don't just "rest" it into the rear bag which will allow for movement. I used to tap mine down into the bag to get the best, snug, fit I could. Something I picked up from the F-Class lads (F-Open).

    Lastly have the rear bag properly filled. Leave no room from manipulation and try stop yourself from squeezing the rear bag. You won't keep the same pressure on it during each shot or even at the moment of firing and this will cause variations in the string.

    As said at the start this feels like telling someone what they already know, but I can't count the amount of times I've forgotten something I knew.

    Forum Charter - Useful Information - RFDs - Ranges by County - Hunting Laws/Important threads


    If you see a problem post use the report post function, "FLAG" & let a Moderator deal with it.


    Your Shooting Forum Moderators - Cass, Cookimonster, Vegeta, Sparks, It wasn't me!



  • Registered Users Posts: 11,659 ✭✭✭✭ Witcher


    no_4 wrote: »
    Could be, but I doubt it, no recoil from a 22 , my guess is inconsistent ammo powder loads

    Even 22lrs recoil.


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  • Registered Users Posts: 431 ✭✭ badaj0z


    We all look for reasons why our accuracy or groups are not as good as we would like. We all tend to the same conclusion, that it is something to do with the kit or external factors that is causing the problem. This gives us the pleasure of buying something to change the result. The reality is that, if a statistical sensitivity study was conducted to establish which of the variables was having the largest effect on output(accuracy), the result would in my experience, show the following :-

    Factor
    Effect %
    Ammo
    10
    Gun
    10
    Sights
    20
    Weather
    5
    YOU
    55

    Look inside for what to improve and remember that consistency is the key factor. .22RF recoil may be low but how you handle it is the difference between 10X or 9x10 plus one 9.


  • Registered Users Posts: 436 ✭✭ JP22


    Overall Cass is pretty close to the mark in his comments on vertical stringing.

    The only solution is to run some tests. I would suggest you shoot the rifle with a solid hold, a medium hold, a light hold and finally shoot it totally free recoil (thumb & finger only) and see if this eliminates or reduces the stringing.

    I used to shoot with the forearm just on the front rest, someone in HH told me to have the forearm positioned 2 or 3 inches forward on the front rest as it aids balance. I also think that after some use time, rear bags need topping up as the sand settles/compacts.

    Just my tuppence worth Clive, see you Sat if your up in HH.


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