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Thread: Help determining if my FSB is canted?, Newbie post.

  1. #21
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    I didn't say that you said that. I just wanted your opinion as to what you thought.

    Quote Originally Posted by Tweak View Post
    I didn't say it was excessive, I said the milspec defined excessive since it sounded like he wants a quantitative answer.

    If it was my rifle, yes, that's excessive, I adjust mine as close to zero as possible.



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  2. #22
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    I found a few more posts about troy sights possibly being machined bad and causing a tilt, i'll have to take a closer look at it. My buddie at work has a few different buis that I can try too.

    Eotech is still in the mail so I'm not in a super hurry to figure this out

  3. #23
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    After installing my new Troy Alpha rail I noticed that my BCM 16" middy FSB is canted.

    I always wondered why my rear MBUS was almost all the way to the left, but everyone said its normal and its just the sight.
    Now with the built in sight on the Alpha, the rear sight is dead center, and I can see the shaved FSB canted to the left under the rail.

    Im not really worried about it since I shaved the FSB and it will now just act as a gas block.

    But is it possible that the gas port is not lined up properly?
    The rifle has always functioned fine and certainly doesnt seem under gassed. (Perfect function with Russian ammo with H buffer is good enough for me)

    Im just wondering if BCM lined up the gas port, causing the cant or if the cant is causing the gas port to be slightly covered.
    Last edited by saddlerocker; 11-30-11 at 22:59.

  4. #24
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    Quote Originally Posted by rackham1 View Post
    Gotcha, that's good advice. I guess what I getting at though is it's not the adjustment range that concerns me, but how far off the windage will be downrange from your zero. That's basically what a cant does, right? Zero at 50, then your windage is off at 100... or zero at 100, then your windage is off at 50... am I wrong?

    For me, zero'd windage at 50 but 1-inch right at 100 is within my needs... no concerns for me. Just wondering what the rest of the group would consider acceptable for a HD rifle (understanding that long-range, competition, etc. are a different story).
    This was the same thing I thought until I was corrected on AR15Armory.

    What I was told that even if the front sight post is canted, it won't matter once the rear sight is adjusted left or right. Once they are moved over it will match it whether it 50 yards or 150 yards. It is because you are matching the rear sight to get in line with the front sight even if its way off, it wont matter.

  5. #25
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    Quote Originally Posted by saddlerocker View Post
    After installing my new Troy Alpha rail I noticed that my BCM 16" middy FSB is canted.

    I always wondered why my rear MBUS was almost all the way to the left, but everyone said its normal and its just the sight.
    Now with the built in sight on the Alpha, the rear sight is dead center, and I can see the shaved FSB canted to the left under the rail.

    Im not really worried about it since I shaved the FSB and it will now just act as a gas block.

    But is it possible that the gas port is not lined up properly?
    The rifle has always functioned fine and certainly doesnt seem under gassed. (Perfect function with Russian ammo with H buffer is good enough for me)

    Im just wondering if BCM lined up the gas port, causing the cant or if the cant is causing the gas port to be slightly covered.
    Knowing how BCM installs and checks their FSB's, I can just about gurantee that it was set right from the factory.

    Assuming you re-installed the FSB correctly, the GP will be lined up.



    C4

  6. #26
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    Quote Originally Posted by C4IGrant View Post
    Knowing how BCM installs and checks their FSB's, I can just about gurantee that it was set right from the factory.

    Assuming you re-installed the FSB correctly, the GP will be lined up.



    C4
    Im not saying your wrong, as you clearly know more than I, but I didnt remove the FSB, I cut/shaved it while on the barrel (ghetto, I know)
    And again, from day one my rear windage was almost all the way left, and now dead center with the new built in Troy front flip-up.
    And while probably unrelated, the only thing keeping the handguard cap from spinning freely was the gas tube.

    Both these are moot points now that the handguard cap is removed and the FSB shaved. So no need to have BCM look at it, and not sure what they would do anyhow, considering I hacked it all up.

    ETA: If you are just saying the GP is most likely lined up, I agree. Im not sure if you are addressing the FSB cant or the GP alignment, or both, I may have misread.
    Last edited by saddlerocker; 12-01-11 at 13:24.

  7. #27
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    Quote Originally Posted by saddlerocker View Post

    But is it possible that the gas port is not lined up properly?
    Remove the FSB and you should be able to see the scar on the barrel left from the gas port in the FSB. You can also rotate the FSB 180 and see how the gas port lines up with the hole between sling swivel bosses.

  8. #28
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    Quote Originally Posted by markm View Post
    That flip up, grabasstic excuse for a sight is more likely to be out of whack. Is that one of those Troy creations? They're ALWAYS popping up on the forums with lots of windage required.

    And I agree... the windage is acceptable.. even with the poo sight.
    Took it off and took a close look at it, everything seems straight on it as far as the CNC'ing goes. I dont think the rear sight is the problem although it seems you have an issue with Troy...

    I guess I can try to zero my eotech with the rear sight down and then flip up the sight for a comparison, right? If the rear sight is way off then I would know for sure its the BUIS vs. the FSB being canted too much.

    I have a 552 and a 3x magnifier coming my way soon.

    Steve0

  9. #29
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    I had this same issue a few months ago with a BCM upper. I sent it off to have a DD Lite rail installed and a muzzle break pinned(needed a gun I could take across state lines without having to notify anyone). Anyway, BCM was contacted and they agreed to look at it. I sent it in and they sent it back 2 weeks later good as new. Not saying they will do that for you, but it's worth a shot. Their customer service is outstanding and if it bothers you, it's definitely worth sending the upper in for inspection.

  10. #30
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    Quote Originally Posted by dudshep31 View Post
    I had this same issue a few months ago with a BCM upper. I sent it off to have a DD Lite rail installed and a muzzle break pinned(needed a gun I could take across state lines without having to notify anyone). Anyway, BCM was contacted and they agreed to look at it. I sent it in and they sent it back 2 weeks later good as new. Not saying they will do that for you, but it's worth a shot. Their customer service is outstanding and if it bothers you, it's definitely worth sending the upper in for inspection.

    How can I check and see if the barrel's FSB is crooked from the factory? The handuards are already mounted.

    Steve

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