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Thread: SR-15 crowning?

  1. #31
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    Quote Originally Posted by bkb0000 View Post
    "crown" to me is a verb. you crown a muzzle... a muzzle is not a crown.



    A crown


    To crown

  2. #32
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    Sometimes explaining technical terms and details around here is like getting Fanbois to understand why Shrubguns aren't as good!
    Last edited by MistWolf; 10-15-10 at 23:33.

  3. #33
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    Or convincing a gunstore worker that the Navy SEALS don't use ''Bushamster'' rifles.
    We miss you, AC.
    We miss you, ToddG.

  4. #34
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    First, anyone can argue semantics but it is commonly accepted to use the term "crown" as a noun and a verb. IMHO the semantics of language mean very little outside of university english departments, commonly accepted uses and definitions are much more useful in promoting meaningful discourse.

    I'm surprised this topic has generated such debate, the definition here is quite simple. No matter what style or shape a crown is cut in (whether a straight 90 degree crown, recessed crown, 11 degree crown, domed/rounded crown or anything else); as long as it is perpendicular to the bore it is a "correct" crown. There is very little, if any, scientific research to suggest that any particular style is more effective than any other, its usually just a matter of gunsmith preference. The simplest crown to apply perpendicular to the bore is obviously the 90 degree crown assuming the barrel is rotating concentrically in the lathe.
    Usually, a bevel is applied to the crown at a minimum of the depth of the difference in height of the land as compared to the groove. The purpose of this bevel is to remove any tiny burrs created by the tool when cutting the crown that could protrude into the bore. Ideally, this is done through a grinding process with a hone since if the bevel is just cut by angling the tool you may create another burr at the inside edge of the bevel. By using a hone you can remove any burrs, a cutter can create them.

    As an aside, there is a lot of misconception about the superiority of the "11 degree target crown". This theory was proposed by a gentleman with very specific implications. The theory was that an 11 degree crown allowed a less disruptive release of gases from behind the bullet exiting the muzzle WHEN USING BOAT TAIL BULLETS. As I understand it, he did a lot of experimenting on the subject but the results were not empirically proven by scientific results to show any superiority of this design, although it may well be correct in that narrow definition.
    It is interesting how his theory was applied almost universally as a perceived ideal crown for target pistols (many 1911 aficionados are diehard believers in the 11 degree crown) when in fact there are very few if any boat tail bullets used in handgun ammunition and therefore the theory has almost no implications specifically related to handgun accuracy.
    Last edited by Rln_21; 10-20-10 at 05:52.

  5. #35
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    Quote Originally Posted by Rln_21 View Post
    As an aside, there is a lot of misconception about the superiority of the "11 degree target crown". This theory was proposed by a gentleman with very specific implications. The theory was that an 11 degree crown allowed a less disruptive release of gases from behind the bullet exiting the muzzle WHEN USING BOAT TAIL BULLETS. As I understand it, he did a lot of experimenting on the subject but the results were not empirically proven by scientific results to show any superiority of this design, although it may well be correct in that narrow definition.
    It is interesting how his theory was applied almost universally as a perceived ideal crown for target pistols (many 1911 aficionados are diehard believers in the 11 degree crown) when in fact there are very few if any boat tail bullets used in handgun ammunition and therefore the theory has almost no implications specifically related to handgun accuracy.
    Coincidentally most heavy grain match bullets are HPBT. So it makes sense to do it to a rifle.

    A pistol however... I can't see it making a whole world of difference in CQB shooting.
    We miss you, AC.
    We miss you, ToddG.

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