Grouping question

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by bookworm, Dec 30, 2009.

  1. bookworm

    bookworm Well-Known Member

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    Below is a pic from my last outing to the local range (yesterday). I'm still experimenting trying to find the best load for my Remington 300 WM. As you can see, I have 4 pretty good groups and one with a little bit of a flier.

    The last time I shot this rifle for groups at 100yds it (and I) seemed to be a pretty consistent 1" grouper. The consistent pattern looked very much like the lower right group in the target below (two very close with one outlier). I probably shot 5 groups that followed that pattern in one form or another - some a little under 1" some a little over 1".

    I have a couple questions...

    The only thing (that I'm aware of) that changed from my 1" session and this session that is closer to 1/2" is that I changed the scope from an older 3-9x Leupold VX-II to a new Leupold VX-3 4.5-14x LR. I don't think there is anything wrong with the VX-II, so the only thing I can think of is that the 14x sight picture helped me hold tighter. It doesn't feel like that should be the case, however, as 9x at 100yds should be plenty for grouping.

    Has anyone experienced a change like this just from a scope?

    I'm feeling a bit premature in saying that I and my rifle are shooting 1/2" 3-shot groups, but of course that is what I want to say :)

    I plan to go out again and see what happens, but I'm looking for any insight or thoughts on what I might be missing that could cause a change like this.

    In the mean time I'll be loading up some different bullets and powder combinations to see where that gets me. I have some 180gr Accubonds and H4831SC powder to throw in the mix. My goal for this rifle is to be able to turn in targets like the one below on a consistent basis (close to 1/2" average).

    Thanks for any thoughts and insights.

    [​IMG]
     
  2. Buffalobob

    Buffalobob Writers Guild

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    Perhaps a parallax issue with the old scope. Perhaps the same issue is still present in these groups but to a lesser extent.
     

  3. winmagman

    winmagman Well-Known Member

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    Provided mirage isn't a problem I seem to shoot tighter groups with a higher magnification, just seems easier to keep the crosshair exactly where I want it.

    Also, try moving your seating depth in or out .005-.010 this will often eliminate the unwanted flier.

    Chris
     
  4. MTBULLET

    MTBULLET Well-Known Member

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    try to find a target that matches your reticle, this makes it much easier to hold the same each time.
     
  5. bookworm

    bookworm Well-Known Member

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    Thanks for the replies.

    MTBULLET - I have a regular duplex reticle. Do you have an example of what you mean by a target that better matches the reticle?
     
  6. MTBULLET

    MTBULLET Well-Known Member

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    try the refield type, with "thick to thin" type lines wich should match a std. duplex reticle better. this makes it much easier to hold same point on target each time
     
  7. Varmint

    Varmint Well-Known Member

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    If you ever get a chance to look through a 36 power scope when sitting at a bench with sand bags you should be able to see the cross hair move when your heart beats. That go to show you how much movement there is when you shoot a rifle. That is what will make the different in your groups.
     
  8. bookworm

    bookworm Well-Known Member

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    I've never had a chance to look through a good 36x (or even 24x for that matter) rifle scope.

    So are you confirming that the sight picture between a 9x and 14x could (in theory) be the difference I'm seeing...at least in part?
     
  9. Buffalobob

    Buffalobob Writers Guild

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    There could be 40-50 reasons for the difference. The only thing you tell us about is that the scope changed to one that I assume has parallax adjustment and that you are using it to some extent.

    It can be different lot of powder, different ambient temperature at the range affecting either the cartridge or the stock. It could be simply less caffeine or the time spacing between rounds fired or the cleanliness of the barrel. Maybe you had on some thick coats and the recoil was not making you flinch so much.

    None of us actually know!!! We are simply giving you some clues to follow up on based upon the one fact you supplied.
     
  10. bookworm

    bookworm Well-Known Member

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    Thanks for the clues.

    The old scope did not have a paralax adjustment and the new one does, so you make a good point on that one.

    The other variables you mention were all virtually unchanged as far as I can recall.

    I think my next step will be to go shoot again and see if I can repeat the smaller groups. If I can, then I'm leaning toward the paralax and sight picture (from higher mag) combination as the leading cause....and I'll gladly take that outcome.

    If I can't reproduce the smaller groups, well, then maybe I just got lucky (or was particularly sharp) at my last outing to string together a few ~1/2" groups.

    And point taken Bob...I know you certainly don't know for sure if I (the shooter) don't know. I appreciate the clues - they are good food for thought.
     
  11. Tang

    Tang Well-Known Member

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    Sorry for the hijack...

    But I have a question. I have a Zeiss 3.5-10x44 on my Sendero. Will longer shots be a problem because it does not have an adjustable objective ?
     
  12. bookworm

    bookworm Well-Known Member

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    No problem on the highjack...this thread has pretty much run its course anyway.

    You can test your scope at the ranges you are planning to shoot to see how much parallax exists.

    This article on the basics may be helpful to you:

    Parallax in Rifle Scopes

    This thread goes into more detail (it has some good stuff in it):

    The Optics Talk Forums - What exactly is parallax anyway?

    Note the comments regarding the need for parallax adjustment beyond 9X (2/3 down in the thread). Seem to me that 10x is right on the edge of needing adjustment...depending on what you want to achieve (distance, accuracy, etc.).
     
  13. arthurj

    arthurj Well-Known Member

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    The thing about the parallax may not be relevant when comparing those groups at 100 yards because even if the scope does not have parallax adjustment, 99.9% of them are set to be parallax free at 100 yards. 9x to 14x is a huge difference when you are trying to shoot the best groups at 100 yards so that is most likely the difference

    and Tang yes that could be a problem, maybe not big enough to cause a miss on an animal at say 400 yards, but your groups won't be as small as they could be without parallax adjustment. Just put your crosshairs on a target several hundred yards out and move your head around and notice how much the reticle moves
     
    Last edited: Dec 31, 2009
  14. Tang

    Tang Well-Known Member

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    I thought I was doing good with the Zeiss Conquest Target. I guess I should have stepped up to the 4.5-14. I do plan to take my RUM to a 1000 yard range. I know I wont win any contests, but its just for fun.