Accuracy ?

Discussion in 'The Basics, Starting Out' started by edge, Jul 5, 2006.

  1. edge

    edge Well-Known Member

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    This is a general question on when to suspect something OTHER than the load.

    I guess my question is how inaccurate a stable bullet can be when fired from a rifle that is reasonably accurate. At some point the bedding, the scope, the scope rings and bases should become suspect.

    If you were to place a barreled action in a solid machine rest, and ignoring POA how large of a spread could you get, even from a shot out barrel, assuming that the bullet is stable when fired? Could it shoot larger than 6 inches @ 100 yards? 12" ? OR is there no limit?

    thanks,

    edge.
     
  2. Indy

    Indy New Member

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    I don't think there is any limit.

    If a rifle is shooting 6" groups at 100 yards, it's probably not the load. Probably something loose, extremely poor bedding, or the barrel is shot out. Or maybe, just maybe, you are using long heavy bullets which cannot be stabilized well.

    Do you have any specifics?
     

  3. edge

    edge Well-Known Member

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    [ QUOTE ]
    SNIP

    Do you have any specifics?

    [/ QUOTE ]

    If you have a new rifle that you put a scope on and take it to the range to sight in and it shoots say a 6 inch group. Obviously there are many things that COULD cause this, bedding, bad scope, bad rings, crown,etc.

    My question is if the holes are perfectly round @ 100 yards, then the bullets are stable, so can the cartridges ( bullets, powder & powder weight, case, headspace, etc be eliminated from this accuracy problem because it is so bad. IF the load can be eliminated immediately then there would be no need to chase different powders,bullets, AOL, etc, until the REAL problem were found.

    In a nutshell I was hoping that if you fire 5 shots and they are sprayed at the target, you go home and tear the rifle apart since it is a mechanical problem and not a load problem, but if there is no limit on "inaccuracies" then this does not eliminate the load.

    edge.
     
  4. Guest

    Guest Guest

    [ QUOTE ]
    In a nutshell I was hoping that if you fire 5 shots and they are sprayed at the target, you go home and tear the rifle apart since it is a mechanical problem and not a load problem, but if there is no limit on "inaccuracies" then this does not eliminate the load.

    edge.


    [/ QUOTE ]

    A bad Load should just give vertical dispersion - which you can verify with a Chronograph. If it's spraying, I'd guess it must be a mechanical problem.

    When Kirby sent me my fast twist 300 APS/Lilja/RUM it shot slightly over 1/2 MOA @ 100 yards with my first load (fire forming brass). As each load went up in gr. of IMR 4350, the groups opened up. The last group showed no signs of pressure but the group size was over 8" at only 100 yards (all over the paper, not vertical dispersion). I didn't have my chrono that day. I was about to cry. Latter Kirby helped me figure out my scope rail was loose. The gun is a real tack driver now.
     
  5. Bart B

    Bart B Well-Known Member

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    [ QUOTE ]
    A bad Load should just give vertical dispersion - which you can verify with a Chronograph. If it's spraying, I'd guess it must be a mechanical problem.

    [/ QUOTE ]I disagree. A bad load may have very crooked bullets shot in an oversize bore which often produces as much horizontal spread as vertical spread. Even in a tight bore, crooked bullets will have quite a horizontal spread 'cause they leave the muzzle in all directions relative to its axis.
     
  6. Spino

    Spino Well-Known Member

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    Edge,

    give us as much detail about the gun and your loads as you can. Indy asked for more specifics and you answered: If you have a new rifle that you put a scope on and take it to the range to sight in and it shoots say a 6 inch group. Obviously there are many things that COULD cause this, bedding, bad scope, bad rings, crown,etc.

    My question is if the holes are perfectly round @ 100 yards, then the bullets are stable, so can the cartridges ( bullets, powder & powder weight, case, headspace, etc be eliminated from this accuracy problem because it is so bad. IF the load can be eliminated immediately then there would be no need to chase different powders,bullets, AOL, etc, until the REAL problem were found.

    In a nutshell I was hoping that if you fire 5 shots and they are sprayed at the target, you go home and tear the rifle apart since it is a mechanical problem and not a load problem, but if there is no limit on "inaccuracies" then this does not eliminate the load. I think indy was inquiring about the gun & ammo??

    I Agree with Bart B. I have experienced loads that group vertical as much as horizontal. Could you give more spec's on gun, bullets, trigger pull etc... Are the loads you're shooting reloads or factory. Have you checked rifle twist for the right bullet weight? Come on Edge spit it out so we can help you.. Oh, one more thing -- were you letting the barrel cool during sight~in? I've see it happen toooo many times when a individual goes to the range and bangs away shot after shot ends up confused why his gun's not gouping... Boy I know you could fry an egg on that barrel.

    Spino
     
  7. Guest

    Guest Guest

    [ QUOTE ]
    I disagree. A bad load may have very crooked bullets shot in an oversize bore which often produces as much horizontal spread as vertical spread. Even in a tight bore, crooked bullets will have quite a horizontal spread 'cause they leave the muzzle in all directions relative to its axis.

    [/ QUOTE ]

    True. I was assuming he used good components (and had experience with them in another firearm) - perhaps bad assumptions. It could also be flinching, hurricane winds, the flying spaghetti monster or a zillion progressively less likely factors - but given the limited details my guess would be mechanical problem. (BB (Bad Bullets) is also a mechanical problem)

    I have an old factory 670 win - 30-06 that shoots 1.5 MOA reliably when cold. Two shot limit (before letting it cool down) or it sprays. The Chrono shows consistent velocity. Any guess on the ot-six's problem? (My top guess is no floating, no bedding).
     
  8. Spino

    Spino Well-Known Member

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  9. Bart B

    Bart B Well-Known Member

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    [ QUOTE ]
    I have an old factory 670 win - 30-06 that shoots 1.5 MOA reliably when cold. Two shot limit (before letting it cool down) or it sprays. The Chrono shows consistent velocity. Any guess on the ot-six's problem?

    [/ QUOTE ]There's usually one of two things that cause shots to start spraying around after the first few are fired:

    * Barrel's bending from heat expansion 'cause it's not properly stress relieved. Even with the barrel totally free floated and/or the receiver epoxy bedded, it'll still happen. Happens a lot with factory barrels and many aftermarket ones.

    * Shooter's changing his position and/or way he holds or shoots the rifle. Proper coaching and practice will fix this.
     
  10. edge

    edge Well-Known Member

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    It turned out the the majority of the problem was due to not using a HOT primer! Shooting in an underground range the muzzle flash was intense to say the least. The powder was not being consumed properly.

    First 3 shots had a 8.9 inch spread!!

    I went back to shoot over the weekend with a "known to be an OK load", and shot sub MOA. I noticed that the muzzle flash was MUCH less so I tried switching primers in the first load. Not good but under 2 MOA, which at least gives me a place to start. Swapping load weights and trying other powders should get this under moa in short order.

    Thanks for the help /ubbthreads/images/graemlins/smile.gif

    edge.
     
  11. Bart B

    Bart B Well-Known Member

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    [ QUOTE ]
    It turned out the the majority of the problem was due to not using a HOT primer!

    [/ QUOTE ]What primer and powder type/charge in did you use that shot the huge groups?

    I've used the mildest large rifle primer made (RWS 5341) in .308 Win. and three 30 caliber magnums with 10% reduced to maximum loads of several powders. No problems in temperatures from 20 to 110 above zero.
     
  12. edge

    edge Well-Known Member

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    OK, This used to be a Savage model 110 in 30-06.
    I put a cheap 0.458 1:14 barrel on. The barrel fits more like a Remington as it is 1 1/4 diameter at the lug and a straight taper to 0.840 dia.

    I was shooting 65 grains of N120 and a 8mm 200 grain SMK in a 43 grain sabot. I was using a Winchester LRM primer, primed in a 45 acp case. When I switched to a 209 primer things got a lot better. Not great, but better and I know that I will be sub moa shortly. I expect to go up to 70+ grains with this powder to try to find the sweet spot, but may need to switch powder if I can't get it to burn.
    With a BC of .52 this will be stable past 1k and assuming the accuracy comes in it will make for some fun Summer varmint shooting.

    [​IMG]
    (L-R) 45 shockwave, 200 grain SMK, SMK inside of sabot.

    Did I mention that this is a muzzleloader /ubbthreads/images/graemlins/wink.gif

    edge.