verticle stringing

Discussion in 'Reloading' started by bullelk6, Oct 8, 2012.

  1. bullelk6

    bullelk6 Well-Known Member

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    I have a question for the guys that know about this shooting game we all love.I have a 7 ultra that i am having a verticle stringing condition with.The gun is pretty much stock remington j lock 700,it doesnt seem to matter what i feed it it will shoot a nice tight group at 100 but they all climb vertical.What am i doing wrong and how do i fix it?
     
  2. Robinhood493

    Robinhood493 Well-Known Member

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    Maybe the barrel is heating up and causing the to POI to change. Is it free floated? Are you putting the rest at different spots on the forearm?
     

  3. JackinSD

    JackinSD Well-Known Member

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  4. Bullet bumper

    Bullet bumper Well-Known Member

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    I would help if you give more detail about how you shoot the gun , bench rest with rest and rear bags ? Bi-pod and rear bag or no bag ? etc etc.
    What ammo are you using , factory ? reloads ?
    Do you firm up your grip and control recoil or let it push you around ?
    There is many things it could be and most likely a combination of several things working together. Sometimes you have to work through changing several things to get the best result.
    The fact that the gun is stock standard and the group strings vertical as you shoot suggests to me a bedding issue exacerbated by barrel heating .
    If the first cold bore shot after a few fouling shots , hits the mark then the bedding system and barrel floating seems a good place to start .
    Followed by shooting style and recoil control review .
    Also it is possible for a scope to be faulty and do that but usually they also throw the first shot inconsistently .
    After that try different ammo or if reloading try changing seating depths or projectiles as Secant ogive bullets don't like a jump to the lands but Tangent ogive will tolerate some jump.
     
  5. bullelk6

    bullelk6 Well-Known Member

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    Thanks for the replies,now for the things you asked for,i shot the gun on the ground off a short harris bipod and holland rear bag.I shot 1 round waited 10 minutes between shots for each of three shots.The first round hit on center exacly 1 inch high,the next 2 were exactly 1/4 inch above the other.I fired two 3 round groups that are exactly the same.the ammo are factory loads i got with the gun.What they are exactly only god and big green know that secret.the glass is vortex viper pst on 20 moa warne rail with luppy rings,all are tight.I am trying to get this worked out before our bad weather starts and am open to all good ideas on loads for elk and remedies om my trouble.Thanks in advance.
     
  6. Bullet bumper

    Bullet bumper Well-Known Member

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    Check all the action screws are tight. Also if your Harris bipos is a leg notch model don't run it at the lowest un-notched setting as it will bounce about on the springs .
    Come up into a notch position . When you shoot of a bi-pod with some recoil you have to load the bipod just before you fire a shot by pushing it slightly forward also make sure the bi-pod feet have not dug a hole in the dirt if on that kind of surface. If so make sure you push forward enough that the feet don't hit the back of any hole or depression .
    Don't use the modern sniper prone position of straight behnd the gun it is too difficult for some and encourages the stock to go under the correct shoulder croutch position during recoil. Lay at an angle to the gun , comfort is more important .
    So you are telling me that from your first shot went 1" high the next two shots went into a 1/2 inch above that ! What is wrong with that , you have the three shots in a half inch group .
    Could you be forgetting that your Zero could already be the 1 inch high mark to start with.
    It seems to me that you have a good first shot cold bore gun so that is a big plus when most of our shooting rests on that first shot anyway and it can put three shots into a 1/2 inch . I may be reading something wrong but I don't think you have a big problem .
    If I have got it wrong let me know.
     
  7. Bart B

    Bart B Well-Known Member

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    Causes of vertical stringing at 100 yards is typically caused by:

    * Epoxy bedding pad under the first inch or so in front of the receiver. As the barrel heats up, it gets bigger in diameter. That puts more pressure on it where the bedding pad is.

    * Shooter's not putting the rifle butt pad the same place vertically in their shoulder for each shot.

    * Shooter's not putting the same pressure from his cheek on the stock for each shot.

    * Inconsistant pressure on the stock's fore arm from what it's resting on; especially when there's contact at the fore end tip against the barrel.

    * Loose stock screws; either front or back, but not a middle one.

    * Barrel's not stress relieved properly after factory bending to straighten it.

    * Receiver face isn't square with barrel tenon threads and as the barrel heats up, more pressure's put at the high point of contact; either at the top or bottom of the receiver face.

    Oft times folks blame muzzle velocity spread as the culprit. But even a medium size cartridge such as the .308 Win. has only 2/10ths inch vertical shot stringing from a 100 fps velocity spread.
     
  8. bullelk6

    bullelk6 Well-Known Member

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    Thanks for the info on this ,i do believe i have the culprit in hand .I pulled the stock and found the tupperware has a slight bit of interferance from a piece of uneven molded plastic .I am going to trim it and shoot it again.I will order a couple of boxes of factory loads to try for now.Any suggestions on what this thing might like?
     
  9. crazyjz

    crazyjz Member

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    I just happened to run across your post here this morning as I was having my coffee and couldn't help but smile.

    I worked on a friends Remington 700 AAC-SD 700 in .308 for a month trying to eliminate some inconsistencies, one of which was vertical stringing even with custom, ladder tested handloads.

    The easy solution and one that I suspect you may have already considered but ruled out due to budget or other considerations is get a better stock than the "tupperware" one you have.

    Having said that, here is the only way I was able to wring out consistently good groups with his rifle and my handloads.

    - no bi-pod, use a front and rear bag. Make sure to put the front bag as close to the receiver as possible and make sure it is in the same spot every shot.

    - the rifle does not like a "free-recoil" style of shooting. I had to pull the rifle back into my shoulder with consistently good form before I started getting consistently good groups.

    - if you don't reload and factory ammo is all you can get than you're stuck with limited choices. If you reload, try some bullets with a longer bearing surface. At short range, I had great luck with Sierra ProHunters.

    Still,after having said all that, really the only really good way to get better groups is to get a good wood or composite stock, free-float the barrel and bed the action. Once there, you will still have some issues but they will be much smaller!
     
  10. Bart B

    Bart B Well-Known Member

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    Then it's not put back into "battery" the same for each shot.