Cold bore shot group vs Warm bore shot group

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by Alan Griffith, Oct 4, 2007.

  1. Alan Griffith

    Alan Griffith Well-Known Member

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    Ran a test this past 3 mornings. I'd run up the canyon behind my house just at 1st light and shoot 100 yd groups.

    I'd shoot a cold bore shot, then a 2nd and 3rd shot; three mornings in a row.
    [​IMG][/IMG]

    The wide shots at 11, 7 and 1 are the CB shots in that order. They run 3". The wide shot at 2, well thats probably me, a bad piece of brass (wish I had remembered to toss it) or baaaad JuJu. It opens up to 3-3/4". The top of the car was icy and slick and the Harris bipod was not solid.

    All the shots in or touching the red are either 2nd or 3rd shots from 1st, 2nd and 3rd mornings. I called the 3rd shot on the 3rd day to the left at 8 touching the red. Other wise those 5 shots would have gone 3/4"

    The interior of the red square is 3/4".

    My question is this.

    Do I accept the fact that my cold bore groups suck and refrain from shooting beyond 400 yds for elk(3" x 4 = 12" Group).

    Or, I do I take a spotter shot and drill an elk out to say, hell, 1000+ with the 2nd shot.

    And, would you move the zero 1/4" down and left?

    Cartridge is 30-06 Ackley Improved pushing the Nosler 180 BT to 2997 fps. Scope is Mk4 4.5-14x50 w/ TMR reticle.
     
  2. J E Custom

    J E Custom Well-Known Member

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    Cold bore

    Allen

    Look at an earler post dated 9/27/07 under "Bullets,Barrels and Ballistics"
    By SS7mm.

    There was a lot of discussion on this thread

    Maybe this will answer your question's

    J E CUSTOM
     

  3. ss7mm

    ss7mm Writers Guild

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    Looks to me like the cold bore shot at only 100 yards is totally unpredictable and since the first shot counts maybe you should look at the 3 cold bore shots as a 3 shot group and adjust accordingly. The only problem with this is then your "group" average location will be off. Yes your 2nd. and 3rd. shots groups quite well but the first shot is the one that counts.

    If it was me I'd shoot for "groups" at 200 or 300 yards and zero based on the center of the group and then determine my maximum range from the results. I believe it's easier and far more accurate to determine your vertical and horizontal location and dispersion at longer ranges than it is at 100 yards.


    You can't reliably say that a 3" group at 100 yards will equal a 12" group at 400 yards as most guns tend to shoot slightly bigger groups as ranges increase. Have you shot it at 400 yards and if so what were your group sizes? Is this the best load for this gun or do you have time to do more load testing?
     
  4. Boss Hoss

    Boss Hoss Well-Known Member

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    You have a LOT more work to do before you start shooting at big game anmials at 1k LOL.
     
  5. Alan Griffith

    Alan Griffith Well-Known Member

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    Gentlemen,

    Good posts, all! Thanks for the info.

    I have shot out past 400 before. Actually about 400 rounds this past year. Here is 818 just a couple of months back, even though the date stamp is incorrect. That's 4.25" but from a warm barrel. I sometimes shoot out to 1000. Groups in the 12"-15" range. Usually no more than 8" vertical. Again warm barrel since I was working my way out each 100 yds on the 18" gongs. Hit them all.

    [​IMG][/IMG]

    Their is an interesting post over on PLRL.com which discusses the process of taking a spotting shot before actually sending lead at the game.

    Typically, how close can you use a spotting shot and NOT spook game? - Topic Powered by eve community

    Again, thanks!
     
  6. goodgrouper

    goodgrouper Well-Known Member

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    Counting on having something to take a sighter shot at that is near your target is not anything more than a gamble. It might happen, it might not. If there is something there, it would work. But I think it would be better to eleviate the stress in your equipment or get a new barrel.
     
  7. Slopeshunter

    Slopeshunter Well-Known Member

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    Goodgrouper, would you mind explaining a little further what you mean by this.

    tks!
     
  8. NYLES

    NYLES Well-Known Member

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    Thats interesting, here is my issue with it...You have 3, 3 shot groups with the same issue and the way youve done it is a pretty darn good way to look at your repeatabilty...You have proven the first shot groups differently than the rest of the group day after day.

    Now you need to figure out why?

    Im with GG on the fact that reling on a spotter shot is a gamble what if you have time for only one? Your outa gas!

    I would go back put that baby on a bench until I a 1/2 INCH or better 100 yd group....then do your 3 day test again....from a bench.
     
  9. James Jones

    James Jones Well-Known Member

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    I once had dealing with a tactical 308 that was custom built with a Hart barrel I believe , this gun would shoot the cold bore shot 1"high and 3/4" left every time , the following 4 shots would make a nice tight cluster around the 1/2" mark with Factory Federal ammo. We did roughly the same test you did , took it out 5 days in a row but we only fired one shot at the same target from the cold bore , the five day five shot group was just around 3/4". This gun would also throw out the first round from a clean barrel.

    So basicaly you might just have a quirky gun , or their maybe some contact in your barrel channel , your action screws could be in a bind , your action could be in a bind , all of the above things can cause trouble with first round fliers. No matter how great your stock is it will move as the temperature changes , so if your gun sits in the nice warm hose all day and night then gets put out into cold weather their might be some movement and the first shot settles the gun back to its "wanted" shooting position. Now remember by movement I'm talking very small , like in the thousandths..

    Just some things to consider , and I would suggest never shooting a spotter round when hunting , you should be able to call your first shot from a cold bore everytime , if not then their is some sort of problem , like mentioned above , or it could be you and not your gun or load , if your wearing a differant jacket , don't have the same cheek weld , the bi-pod could be preloaded for the first shot or vise versa , their are just to many variables in this test to make an accurate determination on the problem.
     
  10. edge

    edge Well-Known Member

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    IMO, either fix a bedding issue or find a different load. I bet that with either more / less powder, different powder, different bullet you will be able to get the consistency you need.

    edge.
     
  11. Mikecr

    Mikecr Well-Known Member

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    For a hunting rifle, don't even bother with the second & third shots.

    You have the right idea with accepting your current limit. By finding this out, your well on the way to getting what you need.

    Developing loads for CB performance is no different other than it takes a lot more time. Once you've done it your perspectives on real long range shooting will change -bigtime.
     
  12. Alan Griffith

    Alan Griffith Well-Known Member

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    Eleviate?

    GG,

    Would you please expound on "eleviate the stress in your equipment "?

    I hope to not replace the barrel. It's a new 1:11, 3 groove Lilja I just had installed last November and according to my primer count, I've only got a little over 400 rounds through it. It is quite skinny though; .542" at the 26" muzzle.

    JJ,

    I'll be working up some 200 gr Nosler AB and 210 Berger VLD's this Fall/Winter.

    Also, the four mornings I shot, I was wearing the same t-shirt (pretty smelly), shooting over the same Harris bipod, over the same trunk lid, all within 15 minutes of first light, no wind. The 4th group this am put the 1st shot just touching the bottom of the 3rd mornings shot at 1 o'clock. Subsequent 2 shots were again, within the red square.
     
  13. goodgrouper

    goodgrouper Well-Known Member

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    I have to totally disagree with this statement unless it is coming from the POV of trying to find a POI on paper for experimental reasons of a cold bore shot like what Alan is doing. Hunting rifles need to be accurate for more than just one shot and need to be repeatable in case the first shot misses and trying to find a load or troubleshoot problems until you find consistent cold bore shots and subsequent shots if at all possible is a worthy endeavor.
     
  14. goodgrouper

    goodgrouper Well-Known Member

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    It is possible that you have stress in the barrel, stress in your bedding system, stress in the receiver threads with them not being straight, or a recoil lug that is stressed. All of these things could change POI when the heat of the barrel increases and spreads. Troubleshooting this problem is extensive and frustrating for sure. Good luck.