Upper is really loose to lower

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  • Mad Charlie
    Warrior
    • May 2017
    • 827

    Upper is really loose to lower

    What are the latest (or most used) techniques to tighten up the upper to lower receiver fit?

    I got a really sloppy one (to me anyway).

    I have side to side and up and down play.
  • Bowhntr6pt
    Warrior
    • Feb 2017
    • 168

    #2
    O-ring around the rear take down pin stud or an accuwedge. You can make your own, just something that will compress.

    You will hear people say the tension will lead to premature wear... yada, yada, yada... BS... been using similar devices for 15 years and thousands of rounds.

    Comment

    • jurassic
      Warrior
      • Sep 2014
      • 246

      #3
      JP rifles makes oversized pins.

      Comment

      • Kilco
        Chieftain
        • Jan 2016
        • 1201

        #4
        A cheap accuwedge with a razor blade and a little bit of your time will make you happy.

        Comment

        • Mad Charlie
          Warrior
          • May 2017
          • 827

          #5
          Thanks guys, I knew about the Accuwedge, but I guess I missed the O ring trick.
          I might drill and tap the lower for a "tensioning" screw.

          Comment

          • Lastrites
            Warrior
            • Apr 2017
            • 678

            #6
            Drilling and tapping if able is about the best way, note though you may still have some side to side rock if yours is really sloppy and depending on how you set the tension screw it may be necessary to use something to press or tap out the pin.

            Comment

            • just_john
              Chieftain
              • Sep 2012
              • 1565

              #7
              Mad C - I get my tensioning pins from McMaster-Carr [ mcmaster.com ]. They are 1/4-28 x 1/4" lg set screws with a synthetic button on the nose. Drill down thru the lower and tap ( use a quality tap or it will break off in the lower ( don't ask ), and a lot of cutting oil ). I usually counterbore from the bottom side a short distance to clean things up. When done, it will take out the verticle slack and a lot of the lateral movement.

              Comment

              • just_john
                Chieftain
                • Sep 2012
                • 1565

                #8
                As an additional thought, you might consider taking a punch and "stiple" the sides of the lugs on the upper - this will efectively make them a tad wider whcih may help with the lateral stability. Don't overdo it.

                Comment

                • Clarence
                  Bloodstained
                  • Dec 2015
                  • 53

                  #9
                  I've used the NationalMatchShim to tighten the fit of a couple of uppers. Takes a bit to sand to fit, but once done, is a permanent fix. I like it better than the Accuwedge.

                  Last edited by Clarence; 10-11-2017, 01:07 PM. Reason: forgot to add a link

                  Comment

                  • Mad Charlie
                    Warrior
                    • May 2017
                    • 827

                    #10
                    As it turned out, I used the lower from my .50 'Wulf instead of my 5.56. It fit much better for whatever reason (happens to be a S&W).

                    Thanks for the suggestions guys, I learned at least one new trick.

                    Comment

                    • Lastrites
                      Warrior
                      • Apr 2017
                      • 678

                      #11
                      MC that was actually what I did a short while ago, flip flopping uppers to lowers to see which fit which better. In the end all seemed to tighten up across the board when I found the right fix bwtn them.

                      Comment

                      • Brett
                        Bloodstained
                        • Feb 2017
                        • 49

                        #12
                        Originally posted by just_john View Post
                        Mad C - I get my tensioning pins from McMaster-Carr [ mcmaster.com ]. They are 1/4-28 x 1/4" lg set screws with a synthetic button on the nose. Drill down thru the lower and tap ( use a quality tap or it will break off in the lower ( don't ask ), and a lot of cutting oil ). I usually counterbore from the bottom side a short distance to clean things up. When done, it will take out the verticle slack and a lot of the lateral movement.
                        Thanks for that tip John, I was wanting a few of that type of set screw. I was planning on calling Aero Precision to try to talk them into selling me a few. I have an Aero lower with this screw and wanted to modify a few other lowers. Just ordered a box of 'em from McMaster.

                        Comment

                        • Lastrites
                          Warrior
                          • Apr 2017
                          • 678

                          #13
                          Aero tension screw, $2

                          Comment

                          • Brett
                            Bloodstained
                            • Feb 2017
                            • 49

                            #14
                            Well, I guess I could have actually looked on their website for one I have a box of 25 coming my way now. Cost $14.50.

                            Comment

                            • just_john
                              Chieftain
                              • Sep 2012
                              • 1565

                              #15
                              Brett, glad to help. I get my taps from them as well. Pricing is excellent and most things arrive the next day
                              Just center the hole between the pin holes. Drill it from the top down. I like to spot face the bottom side, just makes it look cleaner. When cutting the threads, do it slowly, make a couple of turns and then back up about a turn and then hit it again. This backing up cuts the "hanging chads" loose and keeps from choking things. Use a good cutting oil.

                              Comment

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