Newcomer to Grendel - Wanted to build for 10 years

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  • Pick713
    Unwashed
    • Oct 2016
    • 16

    Newcomer to Grendel - Wanted to build for 10 years

    I used to do a lot of precision rifle shooting and 2 man team precision matches. Had a lot of fun with it and always wanted to build a Grendel for the obvious capabilities of the round. Before i could get things together, life happened, shooting slowed down, and I found myself in the hog hunting world and was using my 6.8 for that. It always nagged at me to build a Grendel SBR and test it on pigs.

    Anyhow, I'm finally there. I purchased a 20' Wilson Barrel through JSE Surplus, Got in on the Faxon Group Buy for the 12" SBR (Barrels being reworked), and I'm ready to build.

    Going back to look at the Wilson Bbl I purchased, it apparently has a .125 bolt face depth chamber. I have an Alexander arms bolt and two of the Faxon bolts, all of which are .136" bolt face depth.

    Could someone link an old thread that might discuss the differences and what type of issues I might have? I ordered the Wilson Barrel as it is supposed to be SAAMI spec'd , but now it looks like I need to pick up a .125" bolt?

    Thanks.
    Last edited by Pick713; 05-17-2017, 10:35 PM.
  • Pick713
    Unwashed
    • Oct 2016
    • 16

    #2
    Found some more info, and it looks like my 0.136 bolts will leave a gap causing a safety issue. My understanding is that the 0.136 depth bolt won't push the round up far enough in the chamber.

    Comment

    • mateba
      Bloodstained
      • Mar 2017
      • 84

      #3
      Welcome. The bolts are not interchangeable. Are you concerned about part uniformity and complicating reloading? You could use a .125 bolt or sell the barrel. It sounds like you have invested in the .136 head-spacing.

      Comment

      • VASCAR2
        Chieftain
        • Mar 2011
        • 6219

        #4
        Welcome to the forum Pick713. JSE Surplus advised another forum member a mistake was made and they recieved barrels chambered to use .125 7.62X39 bolts instead of .136 (bolt face depth) 6.5 Grendel bolts. The 7.62X39 bolt does not have as much clearance/metal for the extractor as a .136 6.5 Grendel bolt. The .136 6.5 Grendel extractor is supposedly beefier and stronger than the .125 bolt extractor.

        Black Hole Weaponry has sold many 264 LBC barrels chambered using the .125 7.62 X39 bolt (Type I). Many owners are satisfied with this bolt and barrel combination. Some people prefer the .125 bolt as it is the same bolt used in their 7.62X39 AR-15's. Aim surplus sell 7.62X39 BCG if you decide to use the Wilson barrel. Colt was the first to develop a 7.62 X 39 AR-15 and chose to use the .136 bolt face depth to accomodate the thicker rim on 7.62X39 cases. Alexander Arms saw advantages to the .136 bolt face depth and uses the .136 bolt with their 6.5 Grendel barrels. Why subsequent vendors of 7.62X39 AR-15 barrels chose to use the .125 bolt is speculation but probably was because the 223/5.56 uses .125 bolt and they did not do the research and testing as done by Colt.

        Previously JSE Surplus sold 6.5 Grendel barrels with AA 6.5 Grendel bolts but in the last few months they have only been stocking barrels chambered to use the .125 X39 bolt.

        Her is a link to the Aim 7.62X39 BCG.


        Last edited by VASCAR2; 05-18-2017, 10:29 AM.

        Comment

        • Pick713
          Unwashed
          • Oct 2016
          • 16

          #5
          Originally posted by mateba View Post
          Welcome. The bolts are not interchangeable. Are you concerned about part uniformity and complicating reloading? You could use a .125 bolt or sell the barrel. It sounds like you have invested in the .136 head-spacing.
          Thank you very much for the information. You are correct in that I am worried about part uniformity and that I have invested in the .136 head spacing. I don't want to have one upper that takes one bolt, and three other uppers that take a different one. Too much chance of something getting swapped and causing an issue. Looks like I'll have a Wilson Bbl for sale.

          Comment

          • Pick713
            Unwashed
            • Oct 2016
            • 16

            #6
            Originally posted by VASCAR2 View Post
            Welcome to the forum Pick713. JSE Surplus advised another forum member a mistake was made and they recieved barrels chambered to use .125 7.62X39 bolts instead of .136 (bolt face depth) 6.5 Grendel bolts. The 7.62X39 bolt does not have as much clearance/metal for the extractor as a .136 6.5 Grendel bolt. The .136 6.5 Grendel extractor is supposedly beefier and stronger than the .125 bolt extractor.

            Black Hole Weaponry has sold many 264 LBC barrels chambered using the .125 7.62 X39 bolt (Type I). Many owners are satisfied with this bolt and barrel combination. Some people prefer the .125 bolt as it is the same bolt used in their 7.62X39 AR-15's. Aim surplus sell 7.62X39 BCG if you decide to use the Wilson barrel. Colt was the first to develop a 7.62 X 39 AR-15 and chose to use the .136 bolt face depth to accomodate the thicker rim on 7.62X39 cases. Alexander Arms saw advantages to the .136 bolt face depth and uses the .136 bolt with their 6.5 Grendel barrels. Why subsequent vendors of 7.62X39 AR-15 barrels chose to use the .125 bolt is speculation but probably was because the 223/5.56 uses .125 bolt and they did not do the research and testing as done by Colt.

            Previously JSE Surplus sold 6.5 Grendel barrels with AA 6.5 Grendel bolts but in the last few months they have only been stocking barrels chambered to use the .125 X39 bolt.

            Her is a link to the Aim 7.62X39 BCG.


            https://www.aimsurplus.com/product.a...ch=7.62X39+BCG
            Thank you very much. Very good info. I bought the Wilson Bbl back in November, and they didn't offer them with Bolts at that time. I inspected the Bbl last night to see if it had any markings to indicate the headspace and it does not. I believe the Bbl was manufactured in September 2016. I wonder if they would have the information to be able to look back at those. Browsing through my emails regarding my original purchase does not provide me with any information regarding this part of the Bbl.

            My understanding is that the bolt face depth also determines the headspace in the chamber, so using a 0.125 headspaced SAMMI Chamber with a 0.136 face depth bolt leaves approximately 0.011 gap between the shoulder of the cartridge and the chamber in the Bbl. If it were a situation where the chamber was 0.136 and I had bolts using the 0.125, I could then have the chamber reamed correct?

            Thank you very much for that link. I got a buddy to buy one of the Bbl's as well as an AA bolt, and feeling a little guilty about it. I'll research further with JSE, and either we're good with the 0.136 bolts, or I'll buy that Aims surplus bolt/carrier combo and swap it out with him for his AA bolt.

            Comment

            • Chrazy-Chris
              Warrior
              • Aug 2015
              • 169

              #7
              Originally posted by VASCAR2 View Post
              Welcome to the forum Pick713. JSE Surplus advised another forum member a mistake was made and they recieved barrels chambered to use .125 7.62X39 bolts instead of .136 (bolt face depth) 6.5 Grendel bolts. The 7.62X39 bolt does not have as much clearance/metal for the extractor as a .136 6.5 Grendel bolt. The .136 6.5 Grendel extractor is supposedly beefier and stronger than the .125 bolt extractor.

              Black Hole Weaponry has sold many 264 LBC barrels chambered using the .125 7.62 X39 bolt (Type I). Many owners are satisfied with this bolt and barrel combination. Some people prefer the .125 bolt as it is the same bolt used in their 7.62X39 AR-15's. Aim surplus sell 7.62X39 BCG if you decide to use the Wilson barrel. Colt was the first to develop a 7.62 X 39 AR-15 and chose to use the .136 bolt face depth to accomodate the thicker rim on 7.62X39 cases. Alexander Arms saw advantages to the .136 bolt face depth and uses the .136 bolt with their 6.5 Grendel barrels. Why subsequent vendors of 7.62X39 AR-15 barrels chose to use the .125 bolt is speculation but probably was because the 223/5.56 uses .125 bolt and they did not do the research and testing as done by Colt.

              Previously JSE Surplus sold 6.5 Grendel barrels with AA 6.5 Grendel bolts but in the last few months they have only been stocking barrels chambered to use the .125 X39 bolt.

              Her is a link to the Aim 7.62X39 BCG.


              https://www.aimsurplus.com/product.a...ch=7.62X39+BCG
              I believe I was the forum member you speak of - the backstory is that JSE sold the Type II (.136) barrels up until a month or two ago and everything was hunky-dory. I bought one in Nov 16 and was happy with it and my AA bolt using factory ammo. When I started reloading for it, I ran into an issue with my reloads "sticking" (which ended up being an issue unrelated to the barrel or bolt), but during my troubleshooting I double checked the description on JSE's website to make sure I was using the right bolt. To my surprise, it said the barrels were Type I (.125). This cast a lot of doubt in whether I was using the right bolt and whether that was causing my sticky reload issue so I emailed them and at first, they gave me false info saying that yes, it uses a Type I (.125) bolt, but when I pressed them (because the facts from my trial and error didn't add up when trying out the bolt off my 7.62x39 upper), they explained that they had received a new batch that came in the Type I (.125) chamber and that is what they are selling now (with bolt included I might add), but when I bought my barrel it may have been from the old (Type II .136) batch. My barrel was purchased in Nov 16 before this new batch so I was good with the .136 bolt. I rented a set of go/no-go gauges to confirm and ease my mind. It sounds like your Wilson is the Type I (.125) which is from their most recent batch. In all my research through this issue, I would've been good with either setup - I just wanted to make sure I was using the right one. You will want to use a 7.62x39 (.125) bolt with your Wilson, which are also available from JSE. Again, there is a lot of debate on this but, in all my research I would've been fine if my setup was like yours and used a 7.62x39 bolt. It was just a matter of figuring out which chamber I had and which bolt it needed.

              Bottom line - looks like you need a 7.62x39 Type I .125 bolt for your Wilson barrel. If you want, you can use a set of go/no-go gauges to confirm (I rented mine from reamerrentals.com for $25 bucks). It's a huge headache, I know. But at least you didn't go through all the crap and confusion that I did. You shouldn't have any issues reloading for both - the ammo will be interchangeable, just remember that your bolts won't be interchangeable. If you want to use the same bolt on both rifles, you'll need to find a different barrel.

              Hope this helps,
              Chris

              Comment

              • Pick713
                Unwashed
                • Oct 2016
                • 16

                #8
                Originally posted by Chrazy-Chris View Post
                I believe I was the forum member you speak of - the backstory is that JSE sold the Type II (.136) barrels up until a month or two ago and everything was hunky-dory. I bought one in Nov 16 and was happy with it and my AA bolt using factory ammo. When I started reloading for it, I ran into an issue with my reloads "sticking" (which ended up being an issue unrelated to the barrel or bolt), but during my troubleshooting I double checked the description on JSE's website to make sure I was using the right bolt. To my surprise, it said the barrels were Type I (.125). This cast a lot of doubt in whether I was using the right bolt and whether that was causing my sticky reload issue so I emailed them and at first, they gave me false info saying that yes, it uses a Type I (.125) bolt, but when I pressed them (because the facts from my trial and error didn't add up when trying out the bolt off my 7.62x39 upper), they explained that they had received a new batch that came in the Type I (.125) chamber and that is what they are selling now (with bolt included I might add), but when I bought my barrel it may have been from the old (Type II .136) batch. My barrel was purchased in Nov 16 before this new batch so I was good with the .136 bolt. I rented a set of go/no-go gauges to confirm and ease my mind. It sounds like your Wilson is the Type I (.125) which is from their most recent batch. In all my research through this issue, I would've been good with either setup - I just wanted to make sure I was using the right one. You will want to use a 7.62x39 (.125) bolt with your Wilson, which are also available from JSE. Again, there is a lot of debate on this but, in all my research I would've been fine if my setup was like yours and used a 7.62x39 bolt. It was just a matter of figuring out which chamber I had and which bolt it needed.

                Bottom line - looks like you need a 7.62x39 Type I .125 bolt for your Wilson barrel. If you want, you can use a set of go/no-go gauges to confirm (I rented mine from reamerrentals.com for $25 bucks). It's a huge headache, I know. But at least you didn't go through all the crap and confusion that I did. You shouldn't have any issues reloading for both - the ammo will be interchangeable, just remember that your bolts won't be interchangeable. If you want to use the same bolt on both rifles, you'll need to find a different barrel.

                Hope this helps,
                Chris
                Thanks Chris. Your response is much appreciated and also adds to my confusion. You purchased yours in November and confirmed it had the 0.136 chamber. I purchased mine in October, just called, and the lady stated it was a .125 Chamber, but her response didn't necessarily give me confidence. I don't recall on their first advertisement for these barrels that it ever listed a bolt type. I still have the email where I saw the advertisement and ordered from, but of course the link no longer works, just takes you to the website. The advertisement said "for the first time, JSE has 6.5 grendel barrels in 20" SS Fluted. SAAMI SPEC," so I assumed all was good.

                Sounds like I'll need to try those go no go gauges as well. Bummer, but I like the Barrel. How does your shoot?

                Comment

                • VASCAR2
                  Chieftain
                  • Mar 2011
                  • 6219

                  #9
                  Sounds like your barrel may in fact be chambered to use the .136 bolt. Whenever I heard of JSE Surplus getting into this SNAFU over .125 & .136 bolts I haven't recommended their 6.5 Grendel barrels to anyone. Either bolt can work and is the reason Black Hole Weaponry signifies barrels chambered to use 7.62X39 .125 bolt as Type I and barrels chamnered with .136 bolt as Type II.

                  Life was sure simpler when 6.5 Grendel SAAMI barrels were only chambered to use .136 bolts. Personally I have only bought 6.5 Grendel SAAMI barrels with .136 bolts.

                  Comment

                  • Pick713
                    Unwashed
                    • Oct 2016
                    • 16

                    #10
                    Originally posted by VASCAR2 View Post
                    Sounds like your barrel may in fact be chambered to use the .136 bolt. Whenever I heard of JSE Surplus getting into this SNAFU over .125 & .136 bolts I haven't recommended their 6.5 Grendel barrels to anyone. Either bolt can work and is the reason Black Hole Weaponry signifies barrels chambered to use 7.62X39 .125 bolt as Type I and barrels chamnered with .136 bolt as Type II.

                    Life was sure simpler when 6.5 Grendel SAAMI barrels were only chambered to use .136 bolts. Personally I have only bought 6.5 Grendel SAAMI barrels with .136 bolts.
                    Okay, well i just ordered the Aim surplus 7.62x39 bolt and carrier. I should be able to use the two different bolts to test for the chamber, correct? If i have a 0.136 Bbl, then the 0.125 bolt shouldn't close on a round. Need a bolt carrier anyway, so I can turn around and sell the bolt if I don't need it, etc.

                    Again, the community response and assistance is greatly appreciated.

                    Comment

                    • Pick713
                      Unwashed
                      • Oct 2016
                      • 16

                      #11
                      Meant to come back and update. With multiple factory loaded rounds, the 7.62 bolt (.125 face depth bolt) would only close on one older PPU loaded round and that was then extremely tight.

                      The .136 bolt closed on all rounds as expected. I feel confident now that my Bbl is a .136 Bbl and was informed incorrectly by JSE when I called them in the exact same way that Chris was.

                      Thanks again for the info on all of this.

                      Comment

                      • VASCAR2
                        Chieftain
                        • Mar 2011
                        • 6219

                        #12
                        Thanks for the update Pick713, glad you got it sorted out!

                        Comment

                        • ah1whiskey
                          Warrior
                          • Sep 2015
                          • 255

                          #13
                          i have one barrel that runs the .125 bolt it is marked 264LBC

                          all the rest are old school barrels with the .135 bolt.

                          so far both types seem to do fine.

                          just don't mix the bcgs!!!

                          Comment

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