What is wrong with this bolt?

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  • Younger
    Warrior
    • Dec 2012
    • 106

    What is wrong with this bolt?

    This bolt came with my old Saturn/Liberty 18 inch barrel from Midway USA. I have shot about 250 rounds of factory and reloaded ammo with this barrel/bolt combo before tearing down the upper and retiring the barrel and bolt to my safe. I decided to build a upper with this barrel/bolt and was in the process of cleaning the BCG when I found the wear on the lugs.
    This barrel has a mid length gas system and the gas port is oversized at .094 so the barrel was wearing a adjustable gas block from the beginning. The chamber is good with factory ammo and I have not had any problems with my reloads. Very accurate barrel.
    Is this bolt safe to shoot with this barrel or should I get another bolt? I have 2 other Grendel's and those bolts show zero wear.

    20160523_162514.jpg20160523_162539.jpg20160523_162604.jpg
  • just_john
    Chieftain
    • Sep 2012
    • 1565

    #2
    Is the wear consistent on all the lugs or is it greater on one side? If your upper is a forged one, did you true the barrel-mating face of the upper before mounting the barrel? Sometimes, with forged uppers, the barrel-mounting face is not perpendicular to the barrel ( travel of the bolt ) which can cause wear patterns that are not consistent around the perimeter of the bolt lugs. All of my uppers are forged ( the only kind I will use ) and I true them all up before mounting the barrel. Most have been off "a little", some more than others.

    Comment

    • A5BLASTER
      Chieftain
      • Mar 2015
      • 6192

      #3
      My bolt from my first grendel uppr had a brownells/saturn barrel and my bolt looked like that when I got ready to sell it so I put a new bolt in it before I sold it and trashed that bolt.

      The bolt I trashed had around 450 to 500 rounds on it from me and i think under a 100 from the guy I bought it from.

      If your upper has not been lapped I would try doing that and get a new bolt and then keep a close eye on it say pulling it and checking for the same wear pattern maybe evey 20 to 30 rounds and keep notes of factory rounds are reloads to see if it starts up again if its a certen ammo thats causing it to do that.

      Thats just my two cents aint worth much but its all I got.

      Comment

      • NugginFutz
        Chieftain
        • Aug 2013
        • 2622

        #4
        In the same vein as the above, it may well be that the receiver face was not true to the bore, which would cause the extension and bolt alignment to be off. This would also mean that whichever weapon that upper is a part of now would have a similar bolt / extension fit issue. A check of that weapon's bolt would likely confirm the diagnosis.

        Under the circumstances, I'd avoid putting that bolt back into service for what should be obvious reasons. I'd also take the advice offered above and take the time to lap the new receiver.
        If it's true that we are here to help others, then what exactly are the others here for?

        Comment

        • A5BLASTER
          Chieftain
          • Mar 2015
          • 6192

          #5
          I had forgot to add that When I changed the bolt I had lapped the reciver at thattime as well but sold it not to long afterwards so I dont know if it fixed that problem are not. The guy who bought it is a member here are was havent seen him post in a long while and cant remeber his name but maybe he will read this and post up if its showing the same signs as yours.

          I have a new upper built with a PF forged upper now and when I got it I checked it and it was perfect no lapping needed I installed a JP barrel and bolt and my bolt doesnt show signs of damage like yours does so maybe it is the face ofthe reciver needs to be lapped and that is whats causing the damage.

          Either way I hope you get it figured out sir.

          Comment

          • Younger
            Warrior
            • Dec 2012
            • 106

            #6
            The wear is consistent on each lug around the bolt. This is a billet upper receiver and was not lapped when this barrel was installed. However the receiver was checked and lapped before the installation of the second barrel. I found the receiver to be very true and only required a few seconds of lapping to prove this. The bolt in the second barrel shows no wear. The bolt lugs are black, consistent with the coating from PF as is my other PF bolt. I have a spare bolt that I will use on my next range session with this rifle. I am thinking that the original bolt was not correctly hardened or was manufactured from a lesser quality material and the coating was inferior. You get what you pay for....the barrel on the other hand is worth every penny. Thanks everyone!

            Comment

            • LRRPF52
              Super Moderator
              • Sep 2014
              • 8569

              #7
              Looks pretty normal to me. I just checked a bolt I have that came with a Satern barrel, and it looks just like that.

              There is a lot of torsion on the bolt lugs with an 18" MLGS with .0935" port, unless you really buffer it heavy and dial down the gas.
              NRA Basic, Pistol, Rifle, Shotgun, RSO

              CCW, CQM, DM, Long Range Rifle Instructor

              6.5 Grendel Reloading Handbooks & chamber brushes can be found here:

              www.AR15buildbox.com

              Comment

              • Rickc
                Warrior
                • Aug 2016
                • 311

                #8
                Do you grease the back of you bolt lugs with something like Phil's tenacious oil

                It will keep bolt.wear down

                Comment

                • lwminton
                  Warrior
                  • Nov 2014
                  • 143

                  #9

                  This is thicker than oil and may stay put better.

                  Comment

                  • Younger
                    Warrior
                    • Dec 2012
                    • 106

                    #10
                    Originally posted by Rickc View Post
                    Do you grease the back of you bolt lugs with something like Phil's tenacious oil

                    It will keep bolt.wear down
                    I have used grease and oil on the back of the bolt lugs. Nothing special purpose. I always grease the lugs on my bolt guns with a Shooters Choice red grease. My two other Grendel's show no wear on the bolt lugs and they get no special treatment. I am going to try a different bolt today and will post my findings. Thanks.

                    Comment

                    • Younger
                      Warrior
                      • Dec 2012
                      • 106

                      #11
                      Update: I installed the new bolt and put 50 rounds of assorted ammo down range. The first thing I noticed was the lack of a small crater in the primers of the fired cases. The craters have been present with the original bolt with all factory Hornady ammo primers and on all my reload primers with the exception of the most mundane starting loads. I use CCI 450 primers when I reload. It appears that the firing pin hole on the original bolt is visibly larger than the hole on the new bolt. Is there a standard size for the hole in Mil spec.
                      I removed the new bolt and inspected the lugs for any wear and found none. Not even a shinny spot anywhere. I had worries that the barrel extension was damaged by the original bolt but it appears ok. I am going to strip the damaged bolt for parts and send the body off to china as scrap. I realize that 50 rounds on a bolt is not a real test but my mind is at ease after seeing the positive results with the changing out of the bolts. I like this new bolt.

                      Comment

                      • Texas
                        Chieftain
                        • Jun 2016
                        • 1230

                        #12
                        Do you know the barrel extension alloy and/or who made it?

                        Comment

                        • Younger
                          Warrior
                          • Dec 2012
                          • 106

                          #13
                          I can only guess that Liberty or Satern built the barrel extension since this is a Liberty barrel. No clue on the alloy.

                          Comment

                          • dammitman
                            Warrior
                            • Dec 2012
                            • 647

                            #14
                            satern and liberty products are iffy,,,,its just the way it is,,,,i have pissed more money away on a liberty barrel than it would have cost to have a good one right from alexander arms or a quality shilen barrel. i cannot tell the difference in it even after sending it to precision firearms. still jams the bullet using factory hornady ammo into the rifling of the barrel,,,,, another waste of money having that "machine work"??? done. just like having been served bad food at a resturant i never send it back,,i just dont ever go back. i wont ever buy another satern product again. plenty of other choices at this point. sure hope i dont find out that alexander arms is using satern to make their barrels!!!!!
                            Last edited by dammitman; 09-11-2016, 12:07 AM.

                            Comment

                            • terrywick4
                              Warrior
                              • Sep 2014
                              • 181

                              #15
                              I have built two guns with Satern barrels and both perform sub moa with no issues.

                              Comment

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