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Thread: The Essentials of a Precision AR-15

  1. #11
    bgrundy Guest
    Thanks for posting this. Good stuff.

    I'd be more interested in seeing changes in grouping with a variety of ammo out at 200 or 300 yds with an AR/.223 platform. 100yds seems a bit short to get a good idea of comparative bullet behavior. Right now I'm limited to 100yds as well, but I'm anxious to see what my new Afgan 14.5 will do with Black Hills match vs. Privi SS109 stuff out at 200, when I get a chance.

    I'm new to this board and completely hooked, BTW. Thanks!

  2. #12
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    Quote Originally Posted by Ratfink View Post
    I know this is a forum and im being the guy i cant stand by saying this but

    those groups are attainable with a high end 14.5-16 in carbine i shoot those groups constantly with my duty rifle

    noveske afghan 14.5 in
    ssa 77gr sierra otm
    US optics SN-4S 1x4
    factory bolt group
    SSA 2 stage trigger

    imho nothing very exotic and my 7 year old daughter is shooting groups in the 1in area

    im not shure how much there is to gain with a higher end bolt group
    I have found that 10 shot groups under an inch from any AR are not very common. 10 shot groups at under 1/2" are spectacular. I have a hard time with your statement that you do it regularly especially with the SSA load.

  3. #13
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    I have a harder time believing that he does it with a Noveske Afghan.

    Noveske barrels are usually 1-1.5 MOA barrels.

    I sooooo want a Kreiger barrelled bolt action gun, or AR.
    We miss you, AC.
    We miss you, ToddG.

  4. #14
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    Quote Originally Posted by epete View Post
    Molon,

    Would you care to elaborate on the Accuracy Node Detection Technique?

    Google only turned up articles on Lymph nodes and circuitry.

    Thanks.
    Google "Ladder Testing". It's really designed for handloaders who can fine tune powder charges in small increments.

    The principle is that during firing, the barrel will whip as the bullet travels the length of the barrel. If the barrel is between the upper and lower nodes, it's whipping quicker compared to when it's whipping as it decelerates to a full stop up or down and changes direction. The idea is to find a powder charge that results in bullet exiting at the muzzle during one of these slow, decelerating whip nodes , ideally when the barrel is at full stop during a direction change. Dispersion will be minimized during these nodes compared to when the barrel is in mid-whip.

    The technique involves loading a round or two with a particular charge, and subsequent rounds at approx .2g increasing charges. Shoot the rounds in order and using a spotting scope/high mag optic, plot on a clean target target where each round hits. What you should find is that charges that equate to mid-whip cycle will plot in a linear fashion, whereas rounds that equate to and end-of-whip/node cycle will cluster tightly. This then becomes your accuracy load, and you should also find that your load is a bit fogiving -- you can be off a tenth or two in powder weight, yet the load will still be accurate.
    Last edited by jmart; 09-29-10 at 10:32.

  5. #15
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    Quote Originally Posted by epete View Post
    Molon,

    Would you care to elaborate on the Accuracy Node Detection Technique?

    Google only turned up articles on Lymph nodes and circuitry.

    Thanks.
    There's a thread talking about it in the SH reloading section.

    http://www.google.com/search?hl=en&q...=&oq=&gs_rfai=

    http://www.the-long-family.com/OBT_paper.htm

  6. #16
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    Good stuff, Molon. Thanks for taking the time to put that together. Impressive 10-shot group, as well. May I ask what scope power you used to achieve that group? May I ask what sort of chamber that barrel has?


    And for Molon and everyone else to consider/ponder/comment on/yell at me about-

    I have seen the three Bs of accuracy mentioned (arranged in order of their importance): Barrel, bullet, and brass. How much does the brass matter, and why? And are we talking about differences between brands of new brass, or brands in general regardless of new, once-fired, or whatever?

    When I've seen the three Bs thrown out in conversation, it has been mostly cut and dried/black and white. Barrel - you need to have a high-quality, match-grade barrel. Bullet - for best accuracy you need to find a bullet your barrel likes to send. Brass - ??? I've never seen any elaboration on the brass aspect other than 'used good brass.' Are they referring to the contents of the brass; as in the primer and the powder?

    And I haven't seen the free-floated handguard wrapped into the barrel point. I might be wrong, but I think the free-floated handguard has more to do with realizing mechanical accuracy potential than brass by itself.



    I noticed Molon pictured two different rifles. One has a muzzle device, the other does not. Does a muzzle device (hider, comp, hider/comp) detract from mechanical accuracy potential at all? If so, are there devices that are worse that others in this context; models that may hamper mechanical accuracy potential more than others? I know swapping different muzzle devices onto a given barrel may change POI, and that a good target crown is probably the best thing if one wants to achieve true precision. But most of the higher-end (by higher-end, I'm thinking reasonable higher-end like Noveske, Ranier, LW/LaRue, WOA, BCM) barrels on the market are threaded for a muzzle device. And some of those barrels are touted as being MOA or better. Are muzzle devices insignificant in the accuracy chain, and I'm just thinking about them too much?



    And what about the chamber and how it relates to accuracy? And what the heck are the specs of the 5.56 NATO Match Chambers (USMC SAM-R Chamber)?
    Last edited by hikeeba; 09-29-10 at 15:05.
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  7. #17
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    Actually, right out of the gate Molon posted Without making this overly complicated, you need three basic components for a semi-automatic AR-15 to produce its best mechanical accuracy (technically, precision): a match-grade barrel, a quality free-float handguard and match-grade ammunition
    Last edited by MistWolf; 09-29-10 at 16:47.

  8. #18
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    Quote Originally Posted by jmart View Post
    Google "Ladder Testing". It's really designed for handloaders who can fine tune powder charges in small increments.
    Thanks for your explanation. I had a feeling that this was what we were discussing. You can't argue that accuracy node detection technique doesn't sound more impressive than ladder testing.

    Quote Originally Posted by johnson View Post
    Thanks, saved for later.

  9. #19
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    Quote Originally Posted by epete View Post
    Molon,

    Would you care to elaborate on the Accuracy Node Detection Technique?

    Google only turned up articles on Lymph nodes and circuitry.

    Thanks.
    The Accuracy Node Detection Technique is simply a tool to aid hand-loaders in determining the specific powder charge that is most likely to deliver the highest level of accuracy (technically precision) from their barrel with a particular powder. Those of you familiar with Creighton Audette’s Incremental Load Development Method (Ladder Test) or Dan Newberry’s Optimal Charge Weight method may recognize that the Accuracy Node Detection Technique is based on the same underlying concepts that those methods are.

    The Accuracy Node Detection Technique (ANDT) is basically a refined, statistically significant version of the ladder test/optimal charge weight method and the ANDT is not dependent upon “interpreting the data” like the previous methods. The ANDT uses much larger effective sample sizes for a greater confidence level and utilizes the mean radius to measure the dispersion of composite shot groups to obtain a more precise identification of the accuracy node of a given barrel/powder combination.
    All that is necessary for trolls to flourish, is for good men to do nothing.

  10. #20
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    To the Moderator who moved this thread from the “AR General Discussion: General topics relating to the AR” forum, to the “Precision Rifle: Bolt guns” forum,

    A semi-automatic AR-15 is not a bolt gun.

    Molon
    All that is necessary for trolls to flourish, is for good men to do nothing.

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