Speaking of AR-15's

The #1 community for Gun Owners of the Northeast

Member Benefits:

  • No ad networks!
  • Discuss all aspects of firearm ownership
  • Discuss anti-gun legislation
  • Buy, sell, and trade in the classified section
  • Chat with Local gun shops, ranges, trainers & other businesses
  • Discover free outdoor shooting areas
  • View up to date on firearm-related events
  • Share photos & video with other members
  • ...and so much more!
  • boisepaw

    boisepaw
    Jan 5, 2015
    380
    Eastern shore, MD
    I pulled out of the back of the safe the Bushmaster Varminter that I've had forever. I recently purchased, from another MDShooter, a 7.62 x 39 upper and thought I would match them up.

    For some reason I can't get both pins back in place with that upper. Which then raises questions for me about the safety of shooting the rifle if the fit doesn't seem just right.

    Any ideas? Or suggestions for where I might find someone trustworthy to look at the set up and see what I might be doing wrong?
     

    ToolAA

    Ultimate Member
    MDS Supporter
    Jun 17, 2016
    10,499
    God's Country
    I pulled out of the back of the safe the Bushmaster Varminter that I've had forever. I recently purchased, from another MDShooter, a 7.62 x 39 upper and thought I would match them up.

    For some reason I can't get both pins back in place with that upper. Which then raises questions for me about the safety of shooting the rifle if the fit doesn't seem just right.

    Any ideas? Or suggestions for where I might find someone trustworthy to look at the set up and see what I might be doing wrong?


    What is the brand of the upper? Can you see any visual misalignment?
     

    omegared24

    Ultimate Member
    Dec 23, 2011
    4,747
    Ijamsville, MD
    Are either cerakoted? If so, the cerakote can mess with tolerances. Might need a light tap with a plastic hammer.

    I have an upper thats off and the front pin hole had a lip on it. I took a light file to the lip and the pin goes in fine.

    Small variances like that shouldn't cause issues with shooting. The main issue you'll have with a 7.62x39 are the magazines. Sometimes they don't feed right and the cartridge will hang up. Mine was reaI bad and I had to grind back the feedramps on my barrel extension so the bullet tip wouldn't catch.
     

    Bertfish

    Throw bread on me
    Mar 13, 2013
    17,606
    White Marsh, MD
    Old style lower perhaps? Colt had those lowers early early on which had different pin spacing. I don't think Bushmaster did that but I'm not sure
     

    GunBum

    Active Member
    Feb 21, 2018
    751
    SW Missouri
    Old style lower perhaps? Colt had those lowers early early on which had different pin spacing. I don't think Bushmaster did that but I'm not sure

    Colt had different large pin diameters, not different pin spacing. Bushmaster only made standard pin lowers and uppers.

    Loose, sloppy AR’s that fall together are less desirable from an accuracy standpoint. There is nothing wrong with the upper/lower needing a little pressure to go together. There are still tolerances for a “milspec” upper and lower. One being on the large end of tolerances, and the other being on the small end of tolerances will make for difficult assemble. Everything can be perfectly safe and within tolerances, and still be hard to go together.


    To assemble:
    Push the front takedown pin in. Swing the upper down onto the lower. Squeeze the upper and lower together, and push in the rear takedown pin. A light tap on the pin with a soft faced mallet may help, and is ok. If you have to beat on it, there’s a problem. Several of my upper/lower combos need a light tap to assemble, and a light tap to disassemble.
     

    outrider58

    Eats Bacon Raw
    MDS Supporter
    Jul 29, 2014
    49,810
    Colt had different large pin diameters, not different pin spacing. Bushmaster only made standard pin lowers and uppers.

    Loose, sloppy AR’s that fall together are less desirable from an accuracy standpoint. There is nothing wrong with the upper/lower needing a little pressure to go together. There are still tolerances for a “milspec” upper and lower. One being on the large end of tolerances, and the other being on the small end of tolerances will make for difficult assemble. Everything can be perfectly safe and within tolerances, and still be hard to go together.


    To assemble:
    Push the front takedown pin in. Swing the upper down onto the lower. Squeeze the upper and lower together, and push in the rear takedown pin. A light tap on the pin with a soft faced mallet may help, and is ok. If you have to beat on it, there’s a problem. Several of my upper/lower combos need a light tap to assemble, and a light tap to disassemble.

    Originally Posted by Bertfish View Post
    Old style lower perhaps? Colt had those lowers early early on which had different pin spacing. I don't think Bushmaster did that but I'm not sure

    The early AR15/M16s had a larger front pin hole on the upper(and lower) where a screw originally attached the front halves together. This should only result in a loose upper-to-lower fit so this should not be the problem.

    Some upper rear pin holes aren't properly elongated and require a bit of fitting.
     

    teratos

    My hair is amazing
    MDS Supporter
    Patriot Picket
    Jan 22, 2009
    59,775
    Bel Air
    The only thing that really matters safety wise is that the bolt locks on a correctly head spaced chamber.
     

    outrider58

    Eats Bacon Raw
    MDS Supporter
    Jul 29, 2014
    49,810
    I pulled out of the back of the safe the Bushmaster Varminter that I've had forever. I recently purchased, from another MDShooter, a 7.62 x 39 upper and thought I would match them up.

    For some reason I can't get both pins back in place with that upper. Which then raises questions for me about the safety of shooting the rifle if the fit doesn't seem just right.

    Any ideas? Or suggestions for where I might find someone trustworthy to look at the set up and see what I might be doing wrong?
    First off, have you had that upper on other lowers?

    Have you had any other uppers on that lower?

    Does the rear of the upper fit flushly with the lower receiver extension when you use only the front pin? If yes, shine a light into the rear pin hole on the 'port' side. You shouldn't see any of the rear takedown lug through the hole. Meaning, you don't want to see anything that would interfear the rear pin going all the way through the two holes(the upper and the lower holes). My suspicion is the problem might lie back there.
     

    gtodave

    Member
    MDS Supporter
    Aug 14, 2007
    14,156
    Mt Airy
    The early AR15/M16s had a larger front pin hole on the upper(and lower) where a screw originally attached the front halves together. This should only result in a loose upper-to-lower fit so this should not be the problem.

    Some upper rear pin holes aren't properly elongated and require a bit of fitting.

    My neighbor just got a Colt with the screw in front pin. I had never seen one before. I wondered how old it was to have that feature.
     

    outrider58

    Eats Bacon Raw
    MDS Supporter
    Jul 29, 2014
    49,810
    My neighbor just got a Colt with the screw in front pin. I had never seen one before. I wondered how old it was to have that feature.

    I have an old AE upper like that also.
    A good workaround is to epoxy a section of aluminum arrow shaft in the hole. It will get rid of the play. 2117 Easton I believe was what I used. Still have the upper.
     

    Valmet

    Member
    Mar 4, 2017
    11
    Crofton, Maryland
    I mated a Bushmaster lower to a Colt upper long ago. I had to use "reverse offset pins" to make it work. They were more sleeves than pins. The lower takedown pins would slide through them to make everything snug. If you did the opposite, a Colt Lower with a Bushmaster upper, I believe you needed regular offset pins, not the reverse ones.
     

    Users who are viewing this thread

    Latest posts

    Forum statistics

    Threads
    274,915
    Messages
    7,258,434
    Members
    33,348
    Latest member
    Eric_Hehl

    Latest threads

    Top Bottom