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Thread: Caribou Project Gun - Opinion/Experience

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    Member highestview's Avatar
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    Default Caribou Project Gun - Opinion/Experience

    So here's the general idea of what I'm going for, but with a scope setup:

    shorty thompson.jpg

    I have a Thompson Center Pro-Hunter with a 223 26" heavy barrel w/ a 1:12 twist. I just ordered the side-folding stock for it. My goal is to shorten the barrel to save a little more weight and make it more compact. The reason being: I've found an excellent caribou spot this year in the walk-in only area and used the .223 to take the caribou.

    I fear changing the barrel in any way because I've gotten 0.3" groups at 50 yards with PMC ammo. I'm hoping the accuracy will be preserved and many people say that seems to be the case. My Ruger scout rifle sure is accurate with a short barrel.

    Looking for opinions on barrel length that will function well with the 55 grain or 62 grain loads (thinking about the Federal XM855). At what length will I actually start losing velocity from the listed velocity on the box? Does anyone know what barrel length Federal chrono's their loads on? Even a 22" barrel would be a nice weight reduction and have an edge over most AR's out there. Has anyone chronographed PMC 55 grain or Federal 62 grain out of a bolt action (22 or 24 in)?

    Also, what type of crown would work best for a 22-24" barrel in 223? Is there any significant choice to be made?
    Born in Alaska: The boundary lines have fallen for me in pleasant places; surely I have a delightful inheritance. Psalm 16:6

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    Quote Originally Posted by highestview View Post
    I fear changing the barrel in any way because I've gotten 0.3" groups at 50 yards with PMC ammo. I'm hoping the accuracy will be preserved and many people say that seems to be the case. My Ruger scout rifle sure is accurate with a short barrel.
    Lots of things effect accuracy and I'll not argue that barrel length will not effect it, but I bet it is the near the bottom of the list.

    Looking for opinions on barrel length that will function well with the 55 grain or 62 grain loads (thinking about the Federal XM855). At what length will I actually start losing velocity from the listed velocity on the box? Does anyone know what barrel length Federal chrono's their loads on? Even a 22" barrel would be a nice weight reduction and have an edge over most AR's out there. Has anyone chronographed PMC 55 grain or Federal 62 grain out of a bolt action (22 or 24 in)?

    Also, what type of crown would work best for a 22-24" barrel in 223? Is there any significant choice to be made?
    I wouldn't go longer than 22" for the purposes you describe (lighter and portable) and would probably look into 20-21". Velocity loss will be real, but it'll not be significant IME. As for what type of crown, anything that is uniform will work fine IME. In contrast to barrel length, the crown has a significant effect upon accuracy. An 11 crown is frequently considered the most accurate type and I've 11 crowns on numerous rifles. I've no firm opinions on the matter and never desired to test the issue, however I do know that a consistent crown is imperative for accuracy. I'd recommend a recessed (90 crown) if you're planning to use the barrel as a tomato stake in the off season, otherwise I do not think it matters at all for your application.
    Foolishness is a moral category, not an intellectual one.

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    Member highestview's Avatar
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    I'm starting to think the 20" is the way to go. I found this on another forum. It seems anything longer than 20" is superfluous on a 223.

    M855 VELOCITY DATA
    __________________________

    7.5" 2244 FPS ...
    10.5" 2639 FPS
    DIFFERENCE 395 FPS
    DIFFERENCE/INCH 132 FPS

    10.5" 2639 FPS ... 14.5" 2861 FPS
    DIFFERENCE 222 FPS
    DIFFERENCE/INCH 56 FPS


    14.5" 2861 FPS ... 16" 2938 FPS
    DIFFERENCE 77 FPS

    DIFFERENCE/INCH 51 FPS

    16" 2938 FPS ... 18" 3046 FPS
    DIFFERENCE
    108 FPS
    DIFFERENCE/INCH 54 FPS

    18" 3046 FPS ... 20" 3061 FPS

    DIFFERENCE 15 FPS
    DIFFERENCE/INCH 7.5 FPS


    I appreciate the crown input.
    Born in Alaska: The boundary lines have fallen for me in pleasant places; surely I have a delightful inheritance. Psalm 16:6

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