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Thread: Serious Problem with DD Fixed Irons on BCM Rifle

  1. #41
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    Quote Originally Posted by Rifleman_04 View Post
    You’ve outlined the institutional differences between services...that’s why we shoot better.
    Lol. Ok.
    RLTW

    Former Action Guy
    Disclosure: I am affiliated PRN with a tactical training center, but I speak only for myself. I have no idea what we sell, other than CLP and training. I receive no income from sale of hard goods.

  2. #42
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    Quote Originally Posted by Rifleman_04 View Post
    So your command sucked then. Unfortunate.

    My Knights BulletFlight Military Version 4.6 for the M4 firing M855 with 25M zero is -0.3@25M and 0.5@300M.
    Perhaps you mean my branch of service not my command, but whatever, dude.

    A trajectory that crosses POA at neither 25M or 300M means a 25M zero = 300M zero? I'm not following your logic.

  3. #43
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    Quote Originally Posted by AndyLate View Post
    A trajectory that crosses POA at neither 25M or 300M means a 25M zero = 300M zero? I'm not following your logic.
    Uh, that’s how it works out in the real world.
    It will never be pinpoint. Day to day the variance in temperature/pressure/ammo will change the poi. Those were the numbers that particular day.
    "Knowledge without experience is just information"--Mark Twain

    Hindsight is 6920

  4. #44
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    Quote Originally Posted by Rifleman_04 View Post
    I’ll stay as long as you’ll have me 😉
    Yea, I just meant this thread, and for you to explain your opinion on why it’s stupid. Are you saying that only optics should be run on FF Rail guns?

  5. #45
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    I'm not Rifleman, or speaking for him but...

    Sights mounted to a free float handguard/rail simply cannot be as precise as sights attached to the barrel. If they are used as short range BUIS, the precision should be adequate and certainly better than point shooting.

    Andy

  6. #46
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    Quote Originally Posted by Patrick_B View Post
    Yea, I just meant this thread, and for you to explain your opinion on why it’s stupid. Are you saying that only optics should be run on FF Rail guns?
    I’m saying irons do belong on FF rail guns but solidly affixed to the barrel. I’m a fan of the Centurion cutout rails for that reason. I’ve seen point of impact shift issues with BCM, Centurion and Geissele rails running buis attached to the rails when the guns are used in other than flat range conditions.
    Last edited by Rifleman_04; 12-03-20 at 08:49.

  7. #47
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    Quote Originally Posted by AndyLate View Post
    I'm not Rifleman, or speaking for him but...

    Sights mounted to a free float handguard/rail simply cannot be as precise as sights attached to the barrel. If they are used as short range BUIS, the precision should be adequate and certainly better than point shooting.

    Andy
    I have observed less deflection in poi on guns with free float rails and fixed front sight base on the barrel when shot off of packs, barriers and bipods while using iron sights.

  8. #48
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    Quote Originally Posted by Rifleman_04 View Post
    I have observed less deflection in poi on guns with free float rails and fixed front sight base on the barrel when shot off of packs, barriers and bipods while using iron sights.
    Absolutely, FF rail and FSB is the best of both worlds.

  9. #49
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    Quote Originally Posted by AndyLate View Post
    Perhaps you mean my branch of service not my command, but whatever, dude.

    A trajectory that crosses POA at neither 25M or 300M means a 25M zero = 300M zero? I'm not following your logic.
    There's a bit of nuance about projectile weight and velocity that affects it - 36yd is preferable for 300m/yd if we're talking 20" barrel 62gr, and it's nice that we can abuse a BDC reticle that allows for quicker/easier 50M verification.

    As far as barrel deflection versus FF handguard deflection, the answer is that barrel mounted will chase some of the imparted loads in various positions, it's as simple as that. Those deviations are all <2moa in the grand scheme of things, and if you can shoot ~5 MOA for an overall probability distribution, you are an Expert marksman by jarhead standards.
    It's not ideal, but I haven't noticed a meaningful difference in spread between my FF railed DD fronts and Centurion FSP setups. The best end-run around that is primarily using an optic, which negates most of those issues.

    The important way to think of it is that optics are just affixed to a receiver that doesn't chase those deflections, so any deviation between FF handguard deflection and what the relative barrel deflection would be at the FSP are still appropriately referenced against what an optic mounted to the upper would be.

    So... short answer is that any differential is completely in the noise compared to how terrible human physiology as an artillery platform realistically is, even under ideal circumstances.
    عندما تصبح الأسلحة محظورة, قد يملكون حظرون عندهم فقط
    کله چی سلاح منع شوی دی، یوازي غلوونکۍ یی به درلود
    Semper Fi
    "Being able to do the basics, on demand, takes practice. " - Sinister

  10. #50
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    I use a DD rear with standard front sight/gas block. My zero is 36 yards and the front post is nearly bottomed out, works for me. The ears for the front sight do a good job of protecting the KNS pin head front I use.

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