Barrel install wiggle fix

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  • sneaky one
    Chieftain
    • Mar 2011
    • 3077

    #16
    Cool find , Stone H. Adapt , improvise as per needed to fit the items together.
    Last edited by sneaky one; 09-02-2017, 01:22 AM.

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    • LtDan
      Warrior
      • Sep 2017
      • 122

      #17
      Anyone ever try the HiTemp Silicone Seal the stuff that it copper colored. I wonder if the rubber had a damping effect on a loose receiver/barrel extension fit

      Comment

      • Sticks
        Chieftain
        • Dec 2016
        • 1922

        #18
        Bad plan. You would still have movement - which you are trying to eliminate.
        Sticks

        Catchy sig line here.

        Comment

        • just_john
          Chieftain
          • Sep 2012
          • 1565

          #19
          The object of the exercise is more than wiggle elimination - it is to insure that everytime things go "bang" that everythings moves, oscillates, wiggles, pushes and pulls in exactly the same manner that it did the previous time that it went "boom". Anything that is less than absolutely rigid incurs some amount of inconsistent and unpredictable response. In the case of barrel mounting, there are no less than two different areas of results.
          The first being "is the barrel really pointing exactly the same way that it ( relative to the sighting device ) was when it was sighted in and the second ( slightly less significant ) does the barrel line up with the bolt in exactly the same way that it did every other time. The first concern is obvious - great / acceptable / lousy consistency of shot arrival vs point of aim. The second can have a serious affect of bolt longevity.
          Bottom line - if it doesn't require a "thermally induced fit ( freeze the barrel / boil the receiver ) then it needs some kind of glue to secure the barrel in place so that it does the same thing, the same way every time it goes "bang".

          Comment

          • The Profit Joseph Sith
            Warrior
            • Nov 2016
            • 596

            #20
            Great thread folks, thanks for all the advice. I'm finally ready to build some uppers and searched the forum. Took a few pages of results to go back but eventually bingo gold mine!

            Do most of you agree that you hand tighten the nut as it cures and then once cured torque? I know typically they say to torque it twice and then one final torque. To me you would apply compound/torque once/cure OR apply compound/cure/torque once.

            On a side note, Ive never really understood the torquing three times process. When i worked at boeing you were only ever allowed to torque any fastener once and it was done. It stretches the fastener and the built in thread lube has done and the CIC plating (Cadmium) will wear etc. Many reasons. The main reason is they said the torque will change after the first time. Also in general for engine builds and heads studs connecting rods and other critical components are the same way.

            I was specifically looking to re read the chemical break downs and whats best. And the torque process.
            I had already purchased the loctite but im thinking I'll get the Indian head shellac now.
            Now i just have to experiment and figure out IFi can throw a extra shim washer in my ALG V0 barrel nut for extra torque. For that higher end toque value. OR maybe cut or broach a square 3/8" or 1/2" socket drive in the alg wrench so i KNOW how much toque is applied.

            Is there any chance we could sticky this? Its great reference info..
            Last edited by The Profit Joseph Sith; 01-01-2018, 01:30 AM.

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            • centerfire
              Warrior
              • Dec 2017
              • 681

              #21
              Originally posted by StoneHendge View Post
              To add to the list of bedding options, I finished up a 6.5 AR10 over the weekend (yes, I'm now also one of THOSE guys. Now I get comments like "I want to get one of those - that's cool - what brand is that?" and "hey, Bobby, check it out - he's shooting a crEEdmoor").

              Put a Proof Research CF barrel on it and when I was on the phone with them asking questions, Mike made sure he went over how they recommend bedding: 1) tight enough to need a heat gun to get it in? Awesome! 2) takes a little effort to get it in.? Green loctite. This is the penetrating stuff. The rational is that it will seek gaps and provide a little fill in those areas. 3) slips right in and maybe even has a bit of play.? Stop by the auto parts store and pick up some Permatex Indian Head Gasket Shellac.

              Well, my barrel slipped right in like the receiver was a five dollar whore. Did a little research and saw the gasket shellac was made for applications up to 350 degrees. I thought: will I be able to get it out if there's a problem with the barrel? I decided if there was a problem and I couldn't get it out, they were getting the receiver along with the barrel since it was their recommendation! Going with their recommendation for bedding could obviously also speed up any process if there was a barrel problem. My local auto parts store didn't have the Permatex but Karl assured me that the Versachem Lion Gasket Shellac was essentially the same ("it just has a Lions Head on the bottle instead of an Indian Head"). It's about as thick as molasses and I spread it evenly on both the extension and inside of the receiver with a flat quarter inch wide watercolor brush). Let it stand a couple of minutes per the instructions and it took quite a bit of effort to get it in. Didn't see any evidence of seepage on the barrel nut as I went through the torque & unscrew process, nor on the chamber side.

              So far so good. I'm certainly not going to have to send the barrel back and as far as I can tell shooting some factory ammo to liberate brass, it looks like it should be at least a 1/2 MOA shooter on the rare occasions that I'm a 1/2 MOA shooter.

              Just figured I'd throw this into the mix given where the recommendation came from.
              This is how I built my last AR10. I had a little seepage into the receiver but it cleaned up easily. The barrel was pretty loose in the receiver to start. I used a 2A upper and Rainier/Shilen Super Match. The rifle shoots.

              Comment

              • Klem
                Chieftain
                • Aug 2013
                • 3506

                #22
                Originally posted by Kswhitetails View Post
                ...The Permatex that was left was obviously heavier on one side than the other, indicating that the extension was a sloppy fit inside the uppers carrier tunnel...
                .
                Ks,

                You've got me thinking...If you squared the front of the upper with the Wheeler tool then why was the glue heavier on one side of the extension than the other?

                Presumably, if the threads on the upper are now square and if the extension is loose going in, when it comes up against the shoulder and the barrel nut tightened it should have exactly the same amount of glue all around it, yes?

                Comment

                • Sticks
                  Chieftain
                  • Dec 2016
                  • 1922

                  #23
                  Providing there was a relatively even application of "glue", and the barrel was inserted centered, not bias towards one side.

                  When I did one of mine, I put a liberal bead around my extension and rotated while inserting into the receiver, removed and repeat a few times to insure an even coating.

                  ETA - The one that I did was my PF Neptune VIII. There was significant slop in the receiver, the receiver was not faced, and all there was for bedding was a small bead around the shoulder, which also bled into the threads quite nicely, thank god it was blue.

                  Upon re-installation of my scope (has been bouncing back and forth between two uppers), I feel that it has made a significant change, and at least both the uppers seem to agree. Elevation variance I can live with between the two, but the windage is 1.5mils off what it was at 100. Spooky change. Both uppers are now keeping the same windage adjustment. I will need to make another trip to verify.
                  Last edited by Sticks; 01-15-2018, 10:35 AM.
                  Sticks

                  Catchy sig line here.

                  Comment

                  • Klem
                    Chieftain
                    • Aug 2013
                    • 3506

                    #24
                    Originally posted by Sticks View Post
                    Providing there was a relatively even application of "glue", and the barrel was inserted centered, not bias towards one side.

                    When I did one of mine, I put a liberal bead around my extension and rotated while inserting into the receiver, removed and repeat a few times to insure an even coating.

                    .
                    I have never glued a barrel but I have to say that if you are going to do it surely you want to fill every bit of air gap with glue for it to work properly. Squeezing the glue out of one side as it's done up doesn't sound like it's going to work. Any air gaps defeat the purpose. Anyone else have thoughts on this?

                    Comment

                    • StoneHendge
                      Chieftain
                      • May 2016
                      • 2009

                      #25
                      Originally posted by centerfire View Post
                      This is how I built my last AR10. I had a little seepage into the receiver but it cleaned up easily. The barrel was pretty loose in the receiver to start. I used a 2A upper and Rainier/Shilen Super Match. The rifle shoots.
                      I've done it a few times now and apply a thin layer on the extension with a cheap El Walmarto watercolor brush. Brush goes into the trash can when I'm done. Haven't had a problem with seepage to date.
                      Let's go Brandon!

                      Comment

                      • centerfire
                        Warrior
                        • Dec 2017
                        • 681

                        #26
                        Originally posted by StoneHendge View Post
                        I've done it a few times now and apply a thin layer on the extension with a cheap El Walmarto watercolor brush. Brush goes into the trash can when I'm done. Haven't had a problem with seepage to date.
                        I probably used too much.

                        Comment

                        • bj139
                          Chieftain
                          • Mar 2017
                          • 1968

                          #27
                          Originally posted by Klem View Post
                          Ks,

                          You've got me thinking...If you squared the front of the upper with the Wheeler tool then why was the glue heavier on one side of the extension than the other?

                          Presumably, if the threads on the upper are now square and if the extension is loose going in, when it comes up against the shoulder and the barrel nut tightened it should have exactly the same amount of glue all around it, yes?
                          If you consider the forces involved: (Directions as viewed from behind rifle in firing position)
                          1. If you are holding the receiver in vise blocks the barrel nut is torqing the barrel extension counterclockwise which pivots around the fixed pin making the loctite thinner on the right side of the receiver.
                          2. If you are holding the barrel with a reaction rod the barrel nut is torquing the receiver counterclockwise which pivots around the fixed pin making the loctite thinner on the left side of the receiver.

                          It seems if you want loctite equally on both sides you should allow the loctite to dry without much torque on the barrel nut or maybe use gravity with the barrel in a vertical position and no barrel nut until dry.

                          Comment

                          • centerfire
                            Warrior
                            • Dec 2017
                            • 681

                            #28
                            Originally posted by bj139 View Post
                            If you consider the forces involved: (Directions as viewed from behind rifle in firing position)
                            1. If you are holding the receiver in vise blocks the barrel nut is torqing the barrel extension counterclockwise which pivots around the fixed pin making the loctite thinner on the right side of the receiver.
                            2. If you are holding the barrel with a reaction rod the barrel nut is torquing the receiver counterclockwise which pivots around the fixed pin making the loctite thinner on the left side of the receiver.

                            It seems if you want loctite equally on both sides you should allow the loctite to dry without much torque on the barrel nut or maybe use gravity with the barrel in a vertical position and no barrel nut until dry.
                            That's how I did it. I use a Wheeler AR15/AR10 upper receiver block clamped vertically. I set the barrel in gasket shellac, wiped off the extra adhesive, and then hand tightened the barrel nut. I let the shellac dry for a few hours then torqued the barrel to 50lb/ft (torqued three times). As I mentioned, I got a little seepage but I probably used too much shellac and the barreled receiver was vertical in the block.

                            Comment

                            • just_john
                              Chieftain
                              • Sep 2012
                              • 1565

                              #29
                              Most of my builds have been loctited. I "paint" it full circumference and seat the barrel in the upper ( mounted vertically ) and tighten the barrel nut until some resistenace is encountered and then let it sit overnight. Then it gets the full torqued process. By doing this, it insures that there is no "stuff" between the flange on the barrel extension and the upper extension. Further, as others have said, I rotate the barrel as it is getting plugged in to insure consistant loctite thickness in the gap.

                              Comment

                              • Kswhitetails
                                Chieftain
                                • Oct 2016
                                • 1914

                                #30
                                I haven't been back here in a while. Sorry Klem, I missed your question, so here I go.

                                In that particular upper receiver, it had already been well loved prior to the mating of this barrel extension. The reason there was more bedding material on one side than the other was a matter of previous wear. ( I believe, all things being equal.) The bedding material did it's job, took the play out of the joint, and the rifle produced much better precision.

                                IF the face of the receiver is square, and IF the tunnel is true, and IF the extension face is square to the bore, the extra material on one side over the other is a good sign; the empty spaces in the union allowing movement have been removed. The barrel nut, properly torqued, WILL square the extension to the face of the receiver, assuming that the faces of both pieces are clean and no material is "shimming" the two apart, and that the aforementioned "ifs" are met.

                                In all actuality, it takes a true set of gauges and tools, not found in most garages, to determine if all of the above "IFs" are true. The bore of the upper being true to the bore of the barrel is the key. You want the bolt to be square to the chamber face and extension lugs at the last moment of lockup and the first moment of release. If the bolt wear wasn't an issue in non-true assembled uppers, the square of the setup wouldn't reallly be an issue at all, we would all just adjust our sights for bullet impact and move forward then being blissfully ignorant of the out-of-square condition. Precision in rifles is about repeat-ability, rather than being "square". The purpose of using bedding material in this case is to allow the shot to be repeated by removing the movement variable of the or "slop" between the barrel extension and upper.

                                SO:

                                The squaring of the receiver face is to lessen or prevent the bolt wear on lockup and unlock, and has nothing to do with precision; As well as to make the overall BCG travel smoother and more reliable. Bedding the barrel removes any possibility of movement between the extension and receiver, making repeated predictable bullet impact a reality.

                                IF you do not see any unusual bolt lug wear, squaring your receiver is unlikely to by itself correct any accuracy issue. IF you cannot pull the barrel from the upper receiver by hand without bedding it, then it is unlikely that bedding the extension will increase accuracy.

                                IF you wish to know rather than guess, then square the receiver, and bed the barrel. Both processes are easily accomplished and both are always absolute in their removal of these two variables in the precision factor of any particular rifle.
                                Nothing kills the incentive of men faster than a healthy sense of entitlement. Nothing kills entitlement faster than a healthy sense of achievement.

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