Point of impact shift.

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by ZeeRo7, May 12, 2015.

  1. ZeeRo7

    ZeeRo7 Member

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    Hello everyone, i am now taking on my long range shooting very seriously and starting to put all my research and newly acquired knowledge of long range shooting into the real world. My rifle is a rather simple setup ive had for a while. Remington 700 cdl .300 win mag with a Nikon buckmaster. Yes I know its not all fancy but definitely a solid setup for me and has served me well. Last time i shot my rifle i had it dialed in perfectly fine, at 100 i shot about .8 and i was happy with it. Hornady 165 gmx. That was last summer though.....went out today and was definitely not where it was supposed to be in terms of POI. I will be shooting A LOT more so i can really get my long range fundamentals into order. But why did my zero get all weird? Same ammo was used...maybe it was just me since i dont shoot it as often as i should?
     
  2. Schnyd112

    Schnyd112 Well-Known Member

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    Anything from barometric pressure changes to a slight headwind could affect your poi. Were you shooting at the same spot? Same angle? Did you Remove any copper fouling before you shot? was your target hung squarely? Does your scope hold zero with the big recoil of that rifle? And as you said at the end of your post, there is always the possibility of user error.

    Keep a log of each day you shoot. Temp, wind, elevation, point of impact, any variables you can think of. Some people even log what they ate the night before and the day of a shoot.
     
  3. ZeeRo7

    ZeeRo7 Member

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    For the most part everything was the same. The optic has held zero very well with my setup. It was about 81* at the warmest in the day. What was strange was that once i was dialed back into place, the next few shots would string off. I would get 2 shots close together and then 1 about 2 inches low. I will say i also noticed once i started shooting at steel 200 it was hitting very consistently. Maybe a bit too much emphasis on "tight groups" had me snagging the trigger. Within such short range for zero confirmation i wouldn't expect barometric pressure to even affect anything. Wind was also calm.
     
  4. Schnyd112

    Schnyd112 Well-Known Member

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    Granted I shoot a much smaller bullet, but I have seen my poi shift 2 inches at 300 yards from shooting first thing in the morning to shooting mid day. Now It was 45 first thing and 80 during the heat of the day. the shift was uniform though, as I was still able to achieve decent groups.

    My 25-06 had some major flyer issues, and we found out the barrel was not concentric to the action. The bottom 4 inches of the rifling was almost completely washed out after less than 100 rounds. It was also a problem we had from day one. Could get 3 of 5 usually to hold but always had flyers, some as bad as 4" at 200 yards. From your explanation this does not sound like the cause.
     
  5. FEENIX

    FEENIX Well-Known Member

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    Check this out >>> http://www.longrangehunting.com/forums/f19/what-happened-my-zero-154044/#post1083409
     
  6. MudRunner2005

    MudRunner2005 Well-Known Member

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    You said you have a CDL... Is it still in the factory CDL wood stock?

    If so, the barometric pressure and temperature differences, and atmospheric moisture content, can cause wood stocks to warp and put pressure on the rifle in a different way than it was before when you sighted it in, causing shifts in your POI.

    For this reason alone, is why a lot of us prefer to use synthetic or fiberglass stocks with aluminum bedding blocks. Those external forces acting on it, take MUCH greater extremes to affect fiberglass or synthetic materials.

    Wood stocks are beautiful, but not really practical for hunting in outside of near-ideal conditions.

    I suggest giving a B&C Medalist Classic, or an HS Precision stock a look.
     
  7. jsthntn247

    jsthntn247 Well-Known Member

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    It's a wood stock, if you havn't taken a wrench to any screws, the wood gun absorbs moisture and heat and in turn shrinks and swells. This causes poi changes because it's moving the action inside the stock and in turn the barrel moves with the action. Have the gun pillar bedded and your problems will go away. I was shooting a 1,000 yard match last weekend and my trigger stopped setting midway through a string. I had to completely take my barreled action out of the stock and adjust the trigger. My first shot when I started back shooting was an X, have your gun pillar bedded and torque the screws to the same in/lbs every time and your poi will not shift.
     
  8. ZeeRo7

    ZeeRo7 Member

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    Thanks guys. All those factors are definitely involved. The wood stock especially. Im gonna shoot again next month and see how it bahaves. I just need more trigger time. Thanks again.
     
  9. Mikecr

    Mikecr Well-Known Member

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    Sounds like oil residue in bore from last cleaning and barrel temp to me(if not something broken).
    This is why it's important(for hunting) to hammer out a system for cold clean bore accuracy, instead of hot grouping.
     
  10. ZeeRo7

    ZeeRo7 Member

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    I didnt patch the bore before shooting to clean out the hoppes in the bore. That could be the possibility. The rifle has always performed real well. My adjustments on the optic were true so the optic is fine. I also am still thinking the bore isnt true yet. Cuz geez when im done shooting, it looks like a solid copper pipe inside lol. More trigger time will determine if im truly the problem which i do think is a huge factor. Once i stopped shooting for groups and decided to have fun and shoot at steel, the shots were well within MOA.