20" Odin barrel build and questions

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  • growling dog
    Unwashed
    • Mar 2017
    • 14

    20" Odin barrel build and questions

    I will try to attach photos below. This is my second AR build and the purpose is for hunting and long range target shooting. The complete rifle with scope and empty magazine weighs 9 lbs. and it is 40 and 1/4 inches in length. I used these parts:

    Anderson lower and upper receivers.
    Odin 20-inch barrel with their BCG and non-adjustable gas block (rifle length gas system).
    15-inch handguard (BCM-KMR-A15).
    Geissele SSA-E trigger(this is the best trigger of any of my guns).
    Magpul ACS-L carbine stock and SL grip.
    Tubb flat buffer spring and 5.3 ounce heavy buffer.
    Surefire 7.63 Procomp compensator.
    Burris E1 Fullfield 4.5x14x42 scope (it has hash marks from 100 to 500 yards and corresponding dots for estimating hold for wind drift).
    Aero scope mount.
    Fake Atlas bipod ($50 Chinese knock-off)

    I shot the rifle last weekend and it functioned without fail. It still dents the brass slightly, so I am going to try shortening the ejector spring. I am kind of disappointed with the 1 1/4 to 1 1/2 inch groups (5 shots, Hornady factory loads at 100 yards) when comparing them to the groups posted on the Grendel forum. Based on some of the forum threads, I probably need to refine my shooting technique by dry firing the rifle and watching for movement on the target. I probably am jerking the trigger sometimes and not following through. I was able to hit the 400 yard gong, after figuring out where to hold. This is the farthest distance I have shot at, so I'm still learning about longer range and the AR. I use an old table to shoot off of and sit on a bucket, but it seems steady.

    I assembled the barrel to the receiver without using Loctite on the extension and without lapping the receiver face. My question is: should I remove the barrel and square the receiver face and bed the barrel extension with Loctite? If I take off the barrel, I will get it cero-coated FDE to match the stock. When I assembled it, the barrel slid right in the receiver, but it didn't seem loose and I torqued the barrel nut to 45 ft. lbs. as specified by BCM. The barrel seems well centered in the hand guard, if it makes any difference. It now has 80 shots through the barrel. I didn't do any barrel break-in procedure.

    Also, when I hold the hand guard and grip, I notice slight movement between the receivers, which bothers me. I am going to try an accu-wedge and maybe make a shim for the pivot pin out of a feeler gauge blade. My other question: is there any other way to remove the play in the receivers? Will this even help? I could try shooting it one more time with the accu-wedge and if it doesn't improve, try bedding the barrel. Any opinions and suggestions will be appreciated.

    Thanks, growling dog
    Attached Files
  • cb4017
    Warrior
    • Dec 2016
    • 183

    #2
    That may just be as good as that particular ammo will shoot in that barrel. I also have an Odin Works barrel and BCG. Best group so far is just over .5" with one of my reloads. I did not use loctite. I also have a bit of play between the receivers but I'm not overly concerned about it. The Army Marksmanship Unit determined years ago that play in the receivers had no effect on accuracy.
    Cliff
    USN Ret., FPD Ret.

    Dues Vult

    Comment

    • Drillboss
      Warrior
      • Jan 2015
      • 894

      #3
      It would be a great case study if you were to establish a solid baseline as is and then square the face and bed the barrel and compare results. Who knows, it might improve things by a few tenths. The bucket and table might account for a couple more tenths.

      That's a great looking rifle with the FDE furniture and unfinished barrel. If it was mine, I don't know if I would Cerakote it.

      Comment

      • Sticks
        Chieftain
        • Dec 2016
        • 1922

        #4
        I'd try a couple more flavors of ammo first. If you get the same results, then it may be worth while facing the receiver, bedding the barrel, and gas block. I don't know what your shooting skill level is, however your indicating some points that may mean the issue is you.

        Try shooting prone - go for the most stable position you can get.

        Make sure your scope rings and base is torqued correctly (Aero has different specs from the norm).
        Sticks

        Catchy sig line here.

        Comment

        • m796rider
          Warrior
          • Jul 2011
          • 398

          #5
          I'd want to make sure the gas block was 100% clear of the handguard; barrel whip can cause a very close-fit gas block to contact the handguard and affect accuracy. Also, see what happens when you shoot without the muzzle brake attached.

          If you're still new to ARs (not sure based on this being your second build) -- shooting a semiauto with its multiple recoil impulses is harder than shooting a bolt action. You definitely have to have your fundamentals down solidly. Also, are you using a rear bag?

          Comment

          • growling dog
            Unwashed
            • Mar 2017
            • 14

            #6
            Thanks commenters. The handguard has good clearance and I do use a rear bag when shooting from the bench. I am going to try to work up some hand loads and do some more shooting before going to the trouble of bedding the barrel and buying a lapping tool. I am prepping my brass and have a couple of different powders and bullets to try. I would be very happy with 1/2-inch groups. If I bed the barrel and lap the receiver I will report back whether it makes any difference in the accuracy.

            Comment

            • just_john
              Chieftain
              • Sep 2012
              • 1565

              #7
              Some things to consider - if the front face of the upper ( where the barrel attaches ) is not square to the centerline of the barrel bore that will have no effect on accuracy. What will happen is that after you sight in at a particular distance and then move to a different distance, the new point of impact may change in an unexpected direction depending on the actual offset of the barrel. Further, loctiting the barrel is only necessary of the barrel does not fit snuggly in the upper. Other considerations: a forged upper is stronger than a billet one ( this really only matters if there is a mechanical failure - then it may matter greatly! ). If the barrel face is not square to the bore, then not all of the bolt lugs are equally sharing the stresses during ignition of a cartridge which can lead to premature bolt failure depending on the extent of the misalignment.
              I have built a significant number of MSR's and will only use forged receivers. BUT, I true them all and they have all needed it to varying extents. In the long term, the tool to true the front face is a very worthwhile investment.
              Regarding some play between the upper and lower receiver, remember, if it is a really snug fit such that there is no play between them, you may need a hammer to get the pins out. A little play is necessary. I do drill and tap the lower and install a "snubber" - a 1/4-20 set screw with a hard nylon insert to put a little pressure on the upper to minimize the play. Have used the "accu-wedge" things on several and they work.
              In the mean time, welcome to the addictive world of the Grendel.

              Comment

              • kc_edc
                Unwashed
                • Mar 2017
                • 24

                #8
                I am getting similar results from my 20" Odin works barrel. I am new to this type of shooting, so I don't know if I am expecting too much. About 1/4 of my groups end up being sub moa with the remaining 3/4 being between 1.1 and 1.5 moa. Pretty consistent across all the ammo I have tried. Also about 1 out of every 20 to 30 rounds I get a bolt over base malfunction. I have had it happen with every ammo type, every magazine and every buffer weight I have tried. It did seem to happen more when it was brand new, but I have yet to get through a range session with out a malfunction. The bolt always locks back, and everything cycles well manually. I am about 150 rounds into this upper by the way.

                Comment

                • growling dog
                  Unwashed
                  • Mar 2017
                  • 14

                  #9
                  I am updating my earlier post. I tried working up some hand loads with Accurate 2520 and CFE223 and three different bullets. I added an accu-wedge. I tried with and without the muzzle brake. I added a lower height scope mount that fit my face better (Armalite medium height). I concentrated on my shooting technique. I had a couple of friends, who are good shots, shoot the rifle. It still shot the same mediocre 1.25 to 1.5 inch, 5-shot groups.

                  So I purchased a receiver squaring tool and disassembled the rifle last weekend. I squared the receiver and used blue gel permatex (Loctite) to bed the barrel to the receiver and reassembled it. I also installed a new gas tube. I forgot to mention this before, but the original gas tube was bent during shipping, so I straightened it, and used it when I assembled the rifle the first time. I have read somewhere, a straightened gas tube could bend back when it heats up and affect accuracy. The new gas tube is straight. I also went back to an H2 buffer, instead of the heavy one, when I changed the ejector spring.

                  I know it is not the scientific method of changing one variable at a time, but what the hell. So, we will see if these changes improve the groups. If it does not shoot less than the 1-inch Odin barrel guarantee, I am going to contact Odin and see if they will exchange the barrel. I will report back after I shoot the rifle again. It might be a couple of months though.

                  Comment

                  • Kilco
                    Chieftain
                    • Jan 2016
                    • 1201

                    #10
                    I'm actually very excited to see your results from the bedding and trueing of the action.

                    I've been using the Odin Works 16" ultralight, and it has been a real shooter. .5-.75 at 2460 with my 123 eld/8208 handload, and 1 moa with my CFE223/123 eld load at 2500.

                    Comment

                    • growling dog
                      Unwashed
                      • Mar 2017
                      • 14

                      #11
                      Here is another update to my Odin barrel build. After squaring the receiver and bedding the barrel extension, there was no improvement with accuracy.

                      I emailed Odin and explained the situation. They had me send my barrel in for evaluation and testing before they would do a warranty replacement. It took about a month for them to get back to me. They said they shot my barrel and that it did meet their 1-inch accuracy guarantee. Their worst group was 0.95 and the best was .40 inch. I asked a few questions about the testing and ammo they used and they told me the following: They shot three 100 yard groups. The number of shots were 3 and 5, but they didn't specify which ones/groups. They used a standard forged receiver with an Odin 15-inch forearm. They did nothing to the barrel other than wipe it out with Hoppes No. 9. The ammo they used was a hand load with 123 grain Nosler custom competition bullets and 28.4 grains of 8208. I also asked if they had any recommendations for assembling the barrel to the receiver. They said to make sure to use proper torque and that nothing is touching the barrel. They paid for shipping both ways. I was surprised they were able to get such good groups compared to what I was getting.

                      I have assembled the returned Odin 20-inch barrel back to the same upper components as I used before. Although the gas block did not touch the forearm before, it was close enough that you could squeeze them together with normal hand pressure. Maybe they could've touched when fired, which caused the inconsistent groups? To make sure there will be no barrel contact during shooting, I filed down the bottom of the gas block and set screws. I don't see how the barrel can touch anything now. I have also purchased some Nosler competition bullets and a pound of IMR8208 powder to try. I will report back my shooting results.

                      Because I had not been able to get less than 1-inch groups with this Odin 20-inch barrel, I decided to try building a second 6.5 Grendel upper using an Alexander Arms 18-inch fluted barrel. I have now shot about 60 rounds through it and I and was able to get a couple of under 1-inch groups(5-shots at 100 yards). Several groups were 1 and 1/8 inch groups. This barrel seems more accurate, and I now know that I can shoot 1-inch groups. I did notice the AA barrel has a shorter throat compared to the Odin barrel, which has about 0.10 longer free bore than the AA. I measured by using a resized case with a notched case neck and bullet pushed into the chamber and rifling by hand to get OAL.

                      Comment

                      • Six5x39
                        Warrior
                        • Sep 2017
                        • 205

                        #12
                        Sweet rifle you got there !

                        Comment

                        • Kilco
                          Chieftain
                          • Jan 2016
                          • 1201

                          #13
                          Thanks for the write up and report..

                          Really hoping to hear you were getting the groups you were looking for..

                          Have you tried any of the 100gr bullets?

                          My 16" Odin Works barrel shoots well with the 123s over 8208.. but when i tried the 100gr BT and 100gr eld-m.... boy oh boy... this thing really loves the lighter bullets..

                          For accuracy, im getting 2680fps with 30.4gr 8208 under either 100gr bullet, most groups are all under 1 moa.

                          For speed, H335 is hard to beat. .1gr under max charge gives 2730 fps.. pretty snappy for a 16".

                          Comment

                          • bj139
                            Chieftain
                            • Mar 2017
                            • 1968

                            #14
                            You might want to try a Lead Sled. It is the best shooting accessory I have bought.

                            The cheaper one for about $70 works great for an AR.

                            Comment

                            • triggerhappy
                              Unwashed
                              • Oct 2017
                              • 1

                              #15
                              I have the 18" Odin barrel and was getting groups similar to the one in the first pic was not happy with them. I tried various powders and bullets never got consistancy out of it. Being I shoot suppressed ( no flash hider/ brake) I was cleaning this weekend and noticed the crown had a raised circle around the bore. I could feel it with my finger nail, so I did a red neck recrowning. Used a round head screw chucked in a drill to smooth the ring away then used a chore boy copper pad to polish it out. Went out yesterday and it cut my groups VERY dramatically. Went from 1-1.5" groups to .5-.75". It just had a very poor crown. Just as a side note I have a Lothar Walther barreled Grendel that shoots .3 moa out to 400yds 1-1 1/4" groups @ 400yds with little effort.
                              Last edited by triggerhappy; 10-25-2017, 12:49 AM.

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