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Thread: The Essentials of a Precision AR-15

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    The Essentials of a Precision AR-15

    The Essentials of a Precision AR-15





    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, preferably hand-loads tuned for your barrel. (The free-float handguard doesn’t improve the accuracy of the barrel per se, it simply prevents any outside influence from detracting from the accuracy of the barrel.) Anything after that will not immensely improve the mechanical accuracy of the semi-automatic AR-15, but several things can help you, the shooter, shoot to the level of the intrinsic accuracy of your semi-automatic precision AR-15.







    While there are certainly gifted individuals among us that can do amazing things with iron sights, most of us will benefit from using a quality, high-power scope to achieve the highest level of accuracy from a precision AR-15. In order to hit the exact same spot on the target every time, you have to be able to see that you are holding on the exact same spot every time. It’s also important for the scope to be mounted at the proper height and at the correct eye-relief for the particular scope. One of the most common errors I see with scopes mounted on AR-15s is the scope not being mounted far enough forward for its eye-relief. Also, in order to maintain that exact hold throughout the trigger pull, it helps not to be fighting a heavy, gritty, stock trigger. There are a variety of aftermarket triggers now on the market for both standard size trigger pins and the larger Colt trigger pins. Personal preference will definitely play a role in trigger selection. Among the two-stage triggers, I’ve found the Geissele triggers to be the smoothest, lightest, most consistent and most reliable. For single-stage triggers, it’s hard to beat the JP Enterprise Fire Control System. Keep in mind that the JP trigger does require fitting.

    Following the scope and trigger selection, some shooters will find that items like aftermarket grips and stocks will help them achieve a better “fit” with their AR-15. (Shooters don’t all come in the exact same size and shape.) Once you’ve put your precision rig together, you have to find a match-grade factory load that your barrel “likes” or better yet, develop a match-grade handload for it.

    A semi-automatic AR-15 is not going to shoot as accurately as a precision bolt-gun, but today’s precision AR-15s are capable of a level of accuracy that is truly outstanding for a semi-automatic rifle. The 10-shot group pictured below was fired from one of my Krieger barreled semi-automatic AR-15s from a bench-rest at a distance of 100 yards. The barrel has a 1:7.7” twist. I used Sierra 55 grain BlitzKings that were hand-loaded on a Dillon XL-650 progressive press. The load was developed using the Accuracy Node Detection Technique. The group has an extreme spread of 0.452”.













    Last edited by Molon; 09-28-10 at 13:42.
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    Very nice post. I am more of a combat shooter but this proves the ability of the AR platform.
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    I'm curious how much the bolt can affect the accuracy of the AR-15 platfrom. I have an LMT enhanced bolt and noticed that compared to a standard bolt it has smaller lugs. It would seem that how tightly the bolt locked to the barrel would play a big part on how accurate the rifle was. If you have a match grade chamber, but a sloppy bolt could that affect accuracy?

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    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
    Last edited by Ratfink; 09-28-10 at 13:18.

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    As always, your posts are a joy to read!

    Thanks for sharing.

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    Molon,

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

    Google only turned up articles on Lymph nodes and circuitry.

    Thanks.

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    Quote Originally Posted by KG_mauserman View Post
    I'm curious how much the bolt can affect the accuracy of the AR-15 platfrom. I have an LMT enhanced bolt and noticed that compared to a standard bolt it has smaller lugs. It would seem that how tightly the bolt locked to the barrel would play a big part on how accurate the rifle was. If you have a match grade chamber, but a sloppy bolt could that affect accuracy?


    Its like not a bolt gun where the bolt face and lugs are part of the entire bolt group. The AR bolt group is basically 2 main pieces where a bolt gun is one main piece. The AR bolt basically floats in the bolt carrier, and when in the locked position can be moved slightly just be finger pressure.

    I do not believe you would notice any difference between an in spec and within head space USGI carrier and the fancy BCG's due to the above reasons. With a bolt gun accuracy can be improved by blueprinting/truing the action. Its just not possible in an AR to get the tight fit a quality bolt gun has.

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    Thanks for the input. I have been thinking about it all day and what you said makes sense.

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    As always, great post Molon

    Quote Originally Posted by Belmont31R View Post
    Its like not a bolt gun where the bolt face and lugs are part of the entire bolt group. The AR bolt group is basically 2 main pieces where a bolt gun is one main piece. The AR bolt basically floats in the bolt carrier, and when in the locked position can be moved slightly just be finger pressure.

    I do not believe you would notice any difference between an in spec and within head space USGI carrier and the fancy BCG's due to the above reasons. With a bolt gun accuracy can be improved by blueprinting/truing the action. Its just not possible in an AR to get the tight fit a quality bolt gun has.
    The laws of physics don't change just because we're talking about the AR. The interface between the bolt lugs and the recess is important regardless if it's bolt & carrier design or simply a bolt.

    Being a two piece bolt design isn't why headspace is within spec when changing out barrels & bolts. It's because the tolerances are tightly controlled. I believe it's the barrel, barrel extension & barrel nut design that allows the tolerances to be held.

    Not all bolt actions have a one piece bolt body. As I understand it, the Savage use a two piece bolt and a barrel nut. Mauser type bolt actions require the barrel to be screwed into place to a certain torque spec. This makes it difficult to match actions, barrels and bolts so that they are interchangeable without it changing the headspace. Further complicating things is the bolt locks into recesses cut in the action.

    I don't have an AR with me to check, but I don't think you can move an AR bolt back & forth when it's locked into battery That would allow the headspace to change and could cause dangerous fluctuations in pressure. It would also allow the lugs and recesses to be battered to death with each shot. The bolt carrier, yes. That can be moved slightly without unlocking the bolt.

    The only way to determine if a National Match carrier will improve accuracy is to shoot it alongside a normal carrier. The theory is sound as it reduces the axial play of the bolt carrier within the receiver
    Last edited by MistWolf; 09-28-10 at 20:56.

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    Quote Originally Posted by Ratfink View Post
    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 don't know, but it seems like you are agreeing with Molon here:
    Great barrel? Check
    Ammunition matched to barrel? Check
    Free floated barrel? Unsure by specs, but without variable pressure it's irrelevant.

    If you are saying that an "Uber-Bolt" is unnecessary, I agree.
    Jack Leuba
    Director of Sales
    Knight's Armament Company
    jleuba@knightarmco.com

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