Page 2 of 2 FirstFirst 12
Results 11 to 18 of 18

Thread: canted front sight question

  1. #11
    Join Date
    Aug 2006
    Location
    Southern California
    Posts
    1,108
    Feedback Score
    0
    Quote Originally Posted by TWR View Post
    It seems most cant issues tend to be toward the left. Kind of makes me think overtorquing the barrel nut and twisting the barrel, might be a big problem with homebuilds.
    Read through my posts in this thread
    Randall Rausch
    AR15 Barrel Guru
    California Precision Rifle Club founding member

  2. #12
    Join Date
    Aug 2006
    Location
    Oklahoma
    Posts
    463
    Feedback Score
    0
    Please don't ever link this site to the folks over there.

  3. #13
    Join Date
    Sep 2006
    Location
    West Texas
    Posts
    289
    Feedback Score
    0

    Thumbs up

    xxxxx
    Last edited by PALADIN-hgwt; 07-09-09 at 23:52.

  4. #14
    Join Date
    Feb 2007
    Location
    Morehead, Ky
    Posts
    29
    Feedback Score
    0
    I built an AR using a Sabre 16" barrel with a CMT flat top M4 upper. I had the same problem, I had to correct for windage almost all the way left on my BUIS. I thought the FSB was canted, but it turned out the upper reciever was faulty. I took the thing apart many times trying to correct the problem before I realized what was really wrong. I sanded a little off the tab in the upper so I could spin the barrel a little, that corrected the sight but my M4 feedramps didn't line up properly and I could see that my FSB was now canted. I finally gave up after a year of tinkering and bought a whole new upper reciever. Guess what the new one lined up perfectly and I didn't have to put more than a few clicks of adjustment on my BUIS.

    I sent my old upper back to CMT with a letter explaining what was wrong with the thing. I didn't call them, I just sent the thing back. A couple weeks later I got a brand new reciever in the mail. And now that reciever turned into a new gun

    So it may be a long shot but make sure your upper is not faulty before you start pounding on your FSB. If your FSB is canted you should be able to tell by eyeballing it with your Foward handgaurd installed. If it looks straight up while you are looking down your handgaurd you could have a not so flat, flat top.

  5. #15
    Join Date
    Sep 2007
    Posts
    1,105
    Feedback Score
    0

    resurrected for relevance

    I bought an upper which takes several more than 21 rear clicks to the left. I purchased it without BCG or BUIS, but the vendor wants those sent...(option "a")...is that logical, or should the canting be able to be remedied without needing those?

    So I'm thinking about (b) calling around town for a knowledgable gunsmith (probably cost more than shipping, but would keep it local), or...

    (c) smacking it myself with a rubber mallet, since that's what Grant says most guys do anyhow. If you'd advise me to try that, what do you clamp in the vice, the upper receiver?

    ETA: I found the other thread on this: https://www.m4carbine.net/archive/in...p/t-18088.html ...So I think I'll try "C."

    pertinent quotes: C4IGrant08-19-2008, 08:43 AM (in reply to: That wouldn't damage the upper receiver?)

    "No. Just as an FYI, this is how all manufacturers get FSB's straight. "

    C4

    "I have the upper secured and then simply hit the FSB to the left or right (depending on which way it needs to be moved)."
    Last edited by carbinero; 04-16-09 at 05:39.

  6. #16
    Join Date
    Feb 2009
    Location
    O'fallon, MO
    Posts
    249
    Feedback Score
    0
    Quote Originally Posted by TWR View Post
    It seems most cant issues tend to be toward the left. Kind of makes me think overtorquing the barrel nut and twisting the barrel, might be a big problem with homebuilds.
    I thought that instaling the barrel nut was the first thing to a barrel(after rifling and chamber are cut of course) and then the gas port was drilled and FSB was installed.

  7. #17
    Join Date
    Dec 2008
    Location
    TN
    Posts
    400
    Feedback Score
    0
    Quote Originally Posted by Puffy93 View Post
    I thought that instaling the barrel nut was the first thing to a barrel(after rifling and chamber are cut of course) and then the gas port was drilled and FSB was installed.
    Many home builders use barrels that already have the gas port drilled and FSB installed.

  8. #18
    Join Date
    Aug 2006
    Location
    Southern California
    Posts
    1,108
    Feedback Score
    0
    Quote Originally Posted by Puffy93 View Post
    I thought that instaling the barrel nut was the first thing to a barrel(after rifling and chamber are cut of course) and then the gas port was drilled and FSB was installed.
    The barrel EXTENSION determines where TDC (top dead center for non car guys) is located on a barrel.
    Gas port, markings and FSB alignment all key off the barrel extension.
    The barrel nut just holds the barrel in the receiver.
    Randall Rausch
    AR15 Barrel Guru
    California Precision Rifle Club founding member

Page 2 of 2 FirstFirst 12

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •