Did I screw up?

Discussion in 'AR Talk' started by daved20319, Mar 13, 2017.

  1. Mar 13, 2017 #1
    daved20319

    daved20319 XDTalk Member

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    I built my first AR with the standard FSB, thinking it would only be used at 50-100 yards. Got to the range yesterday for some accuracy testing, couple of glitches, biggest being no way to adjust the front sight, so with the post all the way down, it's shooting 6-8" low at 50 yards. The 1:7 barrel definitely doesn't like 55 gr. ammo, looked more like a shotgun pattern rather than a group. Switching to 75 gr. made a huge difference, group size immediately shrunk to 1.5" or so.

    So I think the rifle is capable of MUCH better, but I'm afraid my 57 year old eyes aren't, even with practice. And forget about anything farther out, I really couldn't hold a consistent aim point at 50, never mind 100 or longer. So I'm going to need to scope this thing, but I'm wondering just how much that FSB is going to interfere with my sight picture. And if it does, how do I remove it? I've heard you can bend barrels removing them, if true, how do I avoid it short of replacing the barrel? Assuming it's straight forward, any gas block recommendations, and will my Magpul handguard still work? And as always, what else don't I know? Thanks, guys.

    Dave
     
  2. Mar 13, 2017 #2
    Highcaliber

    Highcaliber XDTalk 500 Member

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    There's no need to remove your FSB, it shouldn't interfere with your sight picture at that focal plane with magnified optics. Most scopes won't focus close enough for the FSB to present much of a problem. The scope mounting height might come into play depending on your configuration.
     
    Last edited: Mar 13, 2017
    • Agree Agree x 2
  3. Mar 13, 2017 #3
    Jonnyuma

    Jonnyuma XDTalk 5K Member

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    What are you using for a rear sight?
    Is the FSB F-marked (for a flattop reciever)?

    The A2 FSB Can be a pain to remove, but it's doable. Make sure you drive the tapered pins from L to R. You can also cut it down leavig the gas system in tact. Any magnification above 3x will pretty much make it disappear, so don't let that be your main concern.This will also allow you to keep your drop-in handguard.

    I think you need an adjustable rear sight if you dont already have one. The elevation adjustment on an A2 type rear sight should allow you to compensate for a possibly mismatched upper reciever/FSB.
     
  4. Mar 13, 2017 #4
    yocan

    yocan XDTalk 15K Member Founding Member

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    Couple things 1 you don't have to remove it. You can see through it with an optic.
    2 1.5" is terrible, have someone else shoot it borrow an optic 4X or higher bag it and you and someone else shoot 5 round groups at 100, if it can't get under 2" at 100 with 55 grain ammo fix the rifle, somethings wrong.
    3. you can get different height pins for the front sight post.
    4 are you using an "F" front sight post and the correct rear?

    Whats your budget. Can we get pics of what you have going on? So of the whole rifle front and rear sight.

    Taking a front sight post off is easy, get a block of wood drill a hole in it for the pin to to go into and set front sight post on the wood and drive the pin out... unless you have a true pencil no issues. You can also just dremel it down, then no need for a new gas block and pinned FSP is the most stable. I did that on a few 20" barrels.
     
  5. Mar 13, 2017 #5
    WantBigBoom

    WantBigBoom XDTalk 500 Member

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    Definitely sounds like a non- F marked front sight base.
     
  6. Mar 13, 2017 #6
    yocan

    yocan XDTalk 15K Member Founding Member

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    Oh did you screw up? Maybe, your barrel nut may be too loose.
     
  7. Mar 13, 2017 #7
    daved20319

    daved20319 XDTalk Member

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    Okay, I'll try and answer as they came up. Yes, it's an F-marked sight base, and I've got the polymer Magpul flip-up rear sight. If I don't have to remove it to mount a scope, all the better. I do have a variety of rings on hand, hopefully one or the other will get me the right height.

    As to the "terrible" accuracy, I'm quite certain the problem is mine, not the rifles. I just suck with iron sights, I've known it for years, but continue to be in denial about it. I do know that every barrel is an individual, the really bad accuracy with the 55 gr. could also be partly due to it not liking that particular brand of ammo. I'm still getting to know this rifle, after yesterday's session, I still only have about 200 rounds through it.

    As to the barrel nut, I didn't assemble the upper, it came fully assembled from PSA. I think the only loose nut I need to worry about is the one behind the trigger :)! Later, and thanks.

    Dave
     
  8. Mar 13, 2017 #8
    yocan

    yocan XDTalk 15K Member Founding Member

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    PSA is known for over not under torquing a barrel. Have someone else shoot this thing before putting money into it.
     
  9. Mar 13, 2017 #9
    daved20319

    daved20319 XDTalk Member

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    No intention of throwing money at this thing, it's sole reason for being was to learn the platform, and do it with a minimum outlay of cash. Not disappointed at all so far, just need to figure out its quirks, and mine. I truly believe the "issues" I'm having are all on me, not the rifle. But I'm also not so invested that if it turns out to be a rifle issue, I'll be more than able to accept it and move on. Already thinking of a second build, this thing NOT being perfect is actually a good thing, I wouldn't learn anything otherwise. Appreciate your time, both here and with the XDs. Later.

    Dave
     
  10. Mar 14, 2017 #10
    daved20319

    daved20319 XDTalk Member

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    Follow-up question for you. What would be the symptoms, if any, of on over torqued barrel? Functionally, this thing has been flawless so far, and that includes unloading a couple of mags as fast as I could, just for the hell of it :twisted:. Is it enough of a potential problem that I should loosen and retorque it myself? Thanks.

    Dave
     

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