Question about AR rifles

Discussion in 'Large-Bore/Small-Bore Rifle/Shotgun' started by ryu_sekai, Aug 27, 2004.

  1. ryu_sekai

    ryu_sekai New Member

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    I have a few questions about AR's rails and triggers

    1.Is a free floating rail system better because it dosent touch the barrel?

    2.What are the advantages of a 2 stage match trigger over regular trigger

    3.1MOA usually refers to the distance between the farthest bullet grouping at 100 yards right?

    4.Is there a certain way I should break in a barrel?

    5.What is the difference between a heavy barrel and a bull barrel?

    thanks
  2. inplanotx

    inplanotx New Member

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    Hello ryu_sekai and welcome to our humble home. It is nice to have you with us. Although I cannot help you with these questions, I am sure one of our more knowledgable members will be along shortly to help you out. Again, nice to have you with us!

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  3. ibffsteve

    ibffsteve New Member

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  4. LDBennett

    LDBennett Well-Known Member

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    ryu_sekai:

    1. Barrels oscillate sinusodially both vertically and horizontally when the cartridge goes off. The end of the barrel actually wips up and down, left to right as the bullet leaves the barrel. Allowing the barrel to be completely free of any part of the rest of the gun assures that the vibrations of the barrel are exactly the same with each shot and that the whipping barrel is in the exact same spot shot to shot as the bullet leaves the barrel. So that means to use this approach nothing that can flex the barrel even minutely can be allowed to touch the barrel. Anything that touches the barel upset the repeatability of the barrel motion (stocks that you touch and pull on are notorious for minutely bending the barrel and changing its frequency of oscillations). Barrels are greatly effected by the sling attachment points mounted to the barrel as well, so stock tubes usually have those items attached to them rather than attached to the barrel.That puts those sling forces directly into the receiver and not into the barrel where such a changeable force can effect shot to shot motion of the barrel.

    2. Staged trigger are personal preferrence. I like single stage triggers as I come from the commercial world of guns and all my other guns are so fitted while a military shooter probably prefers two stage triggers as his world of military guns use two stage triggers mostly for safety reasons. Other two stage trigger user claim other factors for match shooting that lead them to use two stage triggers. Both styles are available for an AR-15 in almost any pull level you might want (see Brownells catalog and web site).

    3. MOA refers to a theoretical cone of one minute of angle that emminates from the barrel of the shooting gun. It works out that that angle on the target at 100 yds equals approximately one inch; 2 inches at 200 yds, 3 inches at 300 yds and so on. The measurement on a shot target is from center to center on the two farthest apart bullet holes. Common groups to shoot are three shot groups (hunting guns), and five shot groups (target guns). The group size is more meaningful if the number of shots is larger as a larger number of shots increases the probability that the next shot will hit inside of the group already established by the previous shots. So some measure ten shot groups. Group shooting should be used as a comparative measure between loads, ammunitions, and other guns shot under the same circumstances.

    4. The web site listed above covers that question pretty well.

    5. There appears to be no standard between manufactures for terminology. So in that light I'll attempt to make a stab at it as I see it. Bull barrel means that the barrel is the same diameter from the root of the barrel at the receiver to the muzzle end. Most other barrels, after the chamber area of the barrel at the receiver end of the barrel, start a taper to the muzzle. In some "weights" of barrels the taper changes as you travel along the barrel so that the barrel has multiple tapers along its length. Light weight barrels start at full diameter and end up very thin at the muzzle while heavy barrels have tapers to them but end up much thicker at the muzzle. Brownells catalog list up to about 10 different "weights" of barrel that are available with single and multiple tapers.

    Hope this helps.

    LDBennett
  5. offeror

    offeror New Member

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    1.Is a free floating rail system better because it dosent touch the barrel?

    Any real free floating system on a weapon will tend to be more independent of the other parts during aim and fire. That can be a good thing because the systems will tend to absorb shock with a bit of elasticity and stay in place. Theoretically the parts should also cooperate better once dialed in. To some extent, you get what you pay for.

    2.What are the advantages of a 2 stage match trigger over regular trigger?

    First, many "regular" or stock triggers on a variety of makes & models are mediocre, so any match trigger which is tuned to give you competition grade advantages may seem like an improvement. A match trigger helps you feel the take-up and the let-off with precision. But let's assume I have a really well-made (or smithed) stock trigger -- it may be heavier, but if it is smooth and doesn't stack on the take-up, I might actually prefer to have that on a practical/defense weapon. What is good on competition, sniper, and long range hunting rifles, like 2-3 lb. trigger breaks, may not be preferable on a practical model -- a stock trigger may be perfectly sufficient, and safer and more controllable under pressure. I would probably not feel the need of a match trigger unless I planned to hunt, or snipe for law enforcement, with my AR.

    3.1 MOA usually refers to the distance between the farthest bullet grouping at 100 yards right?

    Somebody else can sum this up, but I believe your statement is correct as it is applied by gun makers. 1 minute of angle is, I believe, also used to describe the accuracy achieved by match grade ammunition.

    4.Is there a certain way I should break in a barrel?

    Agh! I hate this part too. Check the link; there are some fairly arduous processes I've read for at least some AR barrels.

    5.What is the difference between a heavy barrel and a bull barrel?

    The older thin AR barrels tended to bend when dropped in the field. The newer AR "HBAR" corrects that potential problem by providing a bit more beef to allow the barrel to withstand a lot more knocking around, thereby assuring long-lived accuracy for a stock barrelled HBAR gun. Bull barrels are usually designed for above average, or match, accuracy, though reviews should be read before spending the extra money on a given brand.

    If I've stated anything above poorly or with inaccuracy someone feel free to correct me. I'm always wanting to learn better.
    Last edited: Aug 28, 2004
  6. djohns6

    djohns6 New Member

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    Nothing personal but AR15.com is where it's at for this discusion .
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