Erratic Groups

Discussion in 'Gunsmithing' started by nvairborne308, Sep 30, 2010.

  1. nvairborne308

    nvairborne308 Well-Known Member

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    I want to preface this post by saying I have a new barrel for my rifle that Kevin Cram will be putting on after deer season.

    I have a remington 700 BDL Stainless with the trigger worked in an HS-Precision stock. I have/had a leupold mark 2 4-12 mounted with leupold dovetail rings and bases. I am/was shooting HSM with 168gr berger vlds. I was getting about a 10" group at 100 yds and the spent cases were incredibly hard to extract. This is a brand new rifle so I was stressing....bad! I took the rifle home did a good cleaning and came back with the same results...except.

    On one shooting iteration I was getting the groups down to a stellar 6" spacing. Went down and checked the target, which was unnecessary as I was using shoot-n-see targets, but felt I must be missing something. Yep, 6" group. I got back to the shooting bench, loaded a 168 berger, squeezed the trigger, rifle goes off, no F#!%ing new hole in the target. Ok, maybe I jerked the trigger. Repeat the sequence, no hole again...WTF. Now I'm a little TO'd. I load another and I'm back on the paper! No adjustments were made, but the hole is in the same vicinity of the previous 6" groups. Next shot is in the same vicinity as the previous. And yes, the cases are still difficult to extract.

    Ok, at this point I am ready to run down to the pawn shop and trade the rifle for a single shot .22 cricket, I hear they group well!! I take a restless night to think of the probable causes. I read that bergers are tempermental. I get some new Leupold PRW rings and bases. Remount the scope and buy some cheap wal-mart remington core-lokt ammo. Deep clean the barrel and bore sight the rifle.

    First shot is abot 1/2" low, second shot is 1/2" low about 1/4" away! Cases are easy to extract!! I move the target to 200 yds make some scope adjustments, DEAD ON! I'm getting great groups! WTF!!!

    Can someone explain why that happened???
     
  2. Derek M.

    Derek M. Well-Known Member

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    lots of things could have happened. sounds like the first ammo was too hot for your rifle with difficult extraction. did you inspect the cases for pressure signs? the first scope could have loosened up. I had that happen once.

    I can't imagine a 10" group at 100 yards though with any ammo from a decent rifle. A 6" group, yes.

    Sounds like you need a few less grains of powder in that HSM ammo. Try some Federal ammo too and see how it does. But since that Remmy ammo shot so well, I highly recommend you go back and buy some more of the same LOT number.
     

  3. jlamb

    jlamb Well-Known Member

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    Could be the Bergers. I have not had any luck with them. When using Bergers the COL has to be loaded to each rifle to work correctly. How far off the lands were they loaded or were the Bergers factory?

    This is why I won't use them.
     
  4. bigngreen

    bigngreen Well-Known Member

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    Did you re-try the HSM ammo after doing the above steps? If not that may be an answer! Berger can be temperamental, I've seen some rifle shoot the HSM stuff well and some not so good kinda like what your seeing. They must be kinda hot for your gun or your head spacing is a little long also.
     
  5. Oliveralan

    Oliveralan Well-Known Member

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    Sep 15, 2009
    Do you see ejector marks on your hsm cases? The heavy extraction could be excessive pressure. However since you changes two things (ammo and scope mounts) you can't completely single out the issue.

    If this rifle is meant to shoot anywhere beyond 200yards, forget remington core-lokt...
     
  6. J E Custom

    J E Custom Well-Known Member

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    +1

    Sounds like the COL is off for the Berger's (They may be to long for your rifle).

    Use the Remington Ammo until you figure it out.

    J E CUSTOM
     
    Last edited: Sep 30, 2010
  7. nvairborne308

    nvairborne308 Well-Known Member

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    The HSM ammo was factory.

    I don't see anything wrong with the cases at all. I will double check for pressure signs. The reason I did the bases and rings coupled with different ammo is that I had little time to resolve this problem. What happens to core-lokts after 200yds?

    I did not retry the HSM as I was worried about jacking things up until after deer season.

    So if Bergers are out... I would like a good bullet (factory for now) that I can shoot. I mean if I get Kevin to chamber my barrel to shoot Bergers, am I then going to have issues if I forget my ammo and have to buy bullets at a local "bait and bottle"? Thanks.
     
  8. Derek M.

    Derek M. Well-Known Member

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    With respect to the corelokt ammo, the bullet itself is one of the most proven in history. But, NOT known to be a very accurate bullet when it comes to longer ranges. So for LRH, it is out if you plan on going to 400+ yards. I've personally seen these bullets handloaded do very well to about 350/400 on paper and on KY deer. So, I don't personally have a problem with them inside of sensible ranges for their purposes.