Barrel spec advice

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  • LRRPF52
    Super Moderator
    • Sep 2014
    • 8569

    #16
    Originally posted by mdram View Post
    talk with craddock a bit. when i emailed them last year they were using .264 lbc chamber
    this is the email i was sent

    "We had been making our own blanks but due to the time it takes I've been using Green Mountain as a substitute, they shoot just fine and I hold either on par with Shilen or Douglas. We've been using the .264 LBC chamber for the past year and it's completely fixed the problems we had been having using the Grendel reamer (pressure issues and accuracy limitations). If you want to send a bolt we'll headspace to it, I don't stock them but prefer JP on the Grendel builds."
    They probably got sold a bill of goods on a reamer that was told to them "was SAAMI spec" without being a SAAMI reamer. Happens all the time.

    SAAMI reamer has a .300" neck, .264 LBC-AR has a .295" neck. The only way you're going to see excessive pressure with a new chamber is if it is cut below SAAMI minimum chamber, assuming safe factory ammo. How I've managed to land on safe SAAMI chambers one after another all these years with several different manufacturers must just be a continually coincident occurrence I guess.

    I have come across several chambers that were cut with some other reamer, and wouldn't allow chambering of a new factory cartridge. I finish-reamed them with a Manson SAAMI reamer that was checked with optical comparator and they were then fine.

    If you are only using the rifle for accuracy and don't care about ever shooting steel case through it, then a genuine Les Baer .264 LBC-AR spec chamber is a great chamber, as long as it it held to Les's specs, which he controlled. The big thing here is how much freebore there is with the bullet you're using.

    If you want a Bartlein pipe, I would also talk to Precision Firearms. The PF Bartlein Grendel barrels I've tested have been some of the most accurate AR15s I've ever laid hands on, right there with AA-chambered Satern cut rifled, Krieger, and bull profile Lilja with SAAMI chamber.

    I've shot 5rd and even 9rd groups rapid with various 6.5 Grendels with top-end pipes on them, with group sizes measured in the .3s to .6s. With one particular PF Bart piped upper, I lost count of how many rounds kept going through the same hole at 100yds and had to look at my cartridge box. Several 5rd rows had been expended. I just say 9 rounds because people would have a hard time believing it. I offered to buy that upper from the customer who it was for, but they refused.

    The fastest shipped 20" top-end barrel you will get is from Lilja, the AR740. They have a lighter medium profile under the handguard at .750", RLGS, immaculately-smooth bores. They usually ship the day you order from them. I've built at least 5 different uppers with that barrel, and they make for a surprisingly-lightweight rifle if you use a light handguard, maybe a bit light for a bench gun with a Luth-AR stock, but perfect for a hunter.

    For a target gun, a .800" or heavier profile under the handguard on a 20" will tighten you up from a 1 MOA rifle to .75 MOA or less with good ammo in my experience. I think the most accurate ammo I've fired from them was PF 123gr SMK through PF Bartlein.

    I've also seen and shot rapid-fired .3" to .6" 5rd groups through the Lilja bull barrels with flutes. I've seen 7rd 107gr/8208XBR groups from 20" AA/Satern with SAAMI chamber in the .2s.

    If it were me, I would be leaning to the PF Bart pipe 20" with SAAMI chamber if you want to cut Xs and 10s at 600yds. Square your upper face and bed it, or have PF just do the whole upper for you. You might have a loose-fitting extension tunnel that won't do you any favors unless you shim and bed it.
    Last edited by LRRPF52; 02-20-2018, 09:00 PM.
    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

    • DontWorryScro
      Unwashed
      • Jan 2018
      • 20

      #17
      Originally posted by LRRPF52 View Post
      They probably got sold a bill of goods on a reamer that was told to them "was SAAMI spec" without being a SAAMI reamer. Happens all the time.

      SAAMI reamer has a .300" neck, .264 LBC-AR has a .295" neck. The only way you're going to see excessive pressure with a new chamber is if it is cut below SAAMI minimum chamber, assuming safe factory ammo. How I've managed to land on safe SAAMI chambers one after another all these years with several different manufacturers must just be a continually coincident occurrence I guess.

      I have come across several chambers that were cut with some other reamer, and wouldn't allow chambering of a new factory cartridge. I finish-reamed them with a Manson SAAMI reamer that was checked with optical comparator and they were then fine.

      If you are only using the rifle for accuracy and don't care about ever shooting steel case through it, then a genuine Les Baer .264 LBC-AR spec chamber is a great chamber, as long as it it held to Les's specs, which he controlled. The big thing here is how much freebore there is with the bullet you're using.

      If you want a Bartlein pipe, I would also talk to Precision Firearms. The PF Bartlein Grendel barrels I've tested have been some of the most accurate AR15s I've ever laid hands on, right there with AA-chambered Satern cut rifled, Krieger, and bull profile Lilja with SAAMI chamber.

      I've shot 5rd and even 9rd groups rapid with various 6.5 Grendels with top-end pipes on them, with group sizes measured in the .3s to .6s. With one particular PF Bart piped upper, I lost count of how many rounds kept going through the same hole at 100yds and had to look at my cartridge box. Several 5rd rows had been expended. I just say 9 rounds because people would have a hard time believing it. I offered to buy that upper from the customer who it was for, but they refused.

      The fastest shipped 20" top-end barrel you will get is from Lilja, the AR740. They have a lighter medium profile under the handguard at .750", RLGS, immaculately-smooth bores. They usually ship the day you order from them. I've built at least 5 different uppers with that barrel, and they make for a surprisingly-lightweight rifle if you use a light handguard, maybe a bit light for a bench gun with a Luth-AR stock, but perfect for a hunter.

      For a target gun, a .800" or heavier profile under the handguard on a 20" will tighten you up from a 1 MOA rifle to .75 MOA or less with good ammo in my experience. I think the most accurate ammo I've fired from them was PF 123gr SMK through PF Bartlein.

      I've also seen and shot rapid-fired .3" to .6" 5rd groups through the Lilja bull barrels with flutes. I've seen 7rd 107gr/8208XBR groups from 20" AA/Satern with SAAMI chamber in the .2s.

      If it were me, I would be leaning to the PF Bart pipe 20" with SAAMI chamber if you want to cut Xs and 10s at 600yds. Square your upper face and bed it, or have PF just do the whole upper for you. You might have a loose-fitting extension tunnel that won't do you any favors unless you shim and bed it.
      That's about the most informative answer I could have hoped for. Thank you!
      I'll look into Precision Firearms for my Bartlein goal. Like I said I do want precision at distance but I don't want it to be a full on dedicated bench gun with heavy bull that'd make the overall gun prohibitively weighty. I'd like to have the option of some limited mobility should the opportunity arise. I do have it on a Luth AR, though, because frankly it will most likely be used at the range 99.99% of the time.
      I'm still entertaining various handguard options for the task and there's been some pretty nice recommendations in this thread. Also on my list of parts still to get is rear bag and perhaps a Harris 9"-13" swivel bipod.
      I would definitely just send all my upper parts to Precision Firearms and have them build the whole upper for me where they can make sure the bolt is matched and there's proper fitment throughout.
      Thanks again!

      Edit: Also, thoughts on SJC Titan comp? Use it? Leave it off and go with thread protector?
      Last edited by DontWorryScro; 02-21-2018, 12:34 AM. Reason: Added question

      Comment

      • grayfox
        Chieftain
        • Jan 2017
        • 4295

        #18
        Larger and heavier than you need imo. There are several brakes or comps to choose from, like the voodoo innovations MB (my favorite), lots of guys like the VG6 gamma muzzle brake in 6.5...
        There's some great studies on MBs, look up the precision rifle blog, 6mm, 6.5mm, and 308 and read thru their tests, also TTAG has some writeups on 7.62 MB (you need a 5/8-24 MB for most Grendel barrels).
        Grendels don't have a lot of kick so you might not need one at all. Try it with just the thread protector while you do some research.
        "Down the floor, out the door, Go Brandon Go!!!!!"

        Comment

        • DontWorryScro
          Unwashed
          • Jan 2018
          • 20

          #19
          Originally posted by grayfox View Post
          Larger and heavier than you need imo. There are several brakes or comps to choose from, like the voodoo innovations MB (my favorite), lots of guys like the VG6 gamma muzzle brake in 6.5...
          There's some great studies on MBs, look up the precision rifle blog, 6mm, 6.5mm, and 308 and read thru their tests, also TTAG has some writeups on 7.62 MB (you need a 5/8-24 MB for most Grendel barrels).
          Grendels don't have a lot of kick so you might not need one at all. Try it with just the thread protector while you do some research.
          Maybe I'll keep the Titan in the toolbox for a potential future AR-10 build. Thanks for the info. I'll look into the test results. Aesthetically that Voodoo Innovations MB looks nice. And I am familiar with the VG6 Gamma. The only thing I really need to be wary about as a California resident is that any option I go with not have any flash hiding properties or mention of anything flash reducing/hiding/anything in their sales wording.

          Edit: After looking at test results and taking convenience of parts acquisition into consideration, if I were to have Precision Firearms spinning me up a barrel and building my entire upper from parts anyways I'd probably just have them provide their PF LMD Brake while they were at it.
          Last edited by DontWorryScro; 02-21-2018, 05:09 AM.

          Comment

          • IescapedCali
            Warrior
            • Sep 2017
            • 335

            #20
            I think he is learning why Grendel’s multiply.

            Comment

            • StoneHendge
              Chieftain
              • May 2016
              • 2009

              #21
              Originally posted by DontWorryScro View Post
              Maybe I'll keep the Titan in the toolbox for a potential future AR-10 build. Thanks for the info. I'll look into the test results. Aesthetically that Voodoo Innovations MB looks nice. And I am familiar with the VG6 Gamma. The only thing I really need to be wary about as a California resident is that any option I go with not have any flash hiding properties or mention of anything flash reducing/hiding/anything in their sales wording.

              Edit: After looking at test results and taking convenience of parts acquisition into consideration, if I were to have Precision Firearms spinning me up a barrel and building my entire upper from parts anyways I'd probably just have them provide their PF LMD Brake while they were at it.
              I have a PF LMD on my 18er and it does the job very well - can't go wrong there.

              Too funny that the Cali lawmakers think having one hide their flash is more "dangerous" than limiting muzzle movement.
              Let's go Brandon!

              Comment

              • DontWorryScro
                Unwashed
                • Jan 2018
                • 20

                #22
                Originally posted by StoneHendge View Post
                I have a PF LMD on my 18er and it does the job very well - can't go wrong there.

                Too funny that the Cali lawmakers think having one hide their flash is more "dangerous" than limiting muzzle movement.
                There is no logic to CA law. I've given up trying to make sense of any of it. Mostly it seems they're trying to make AR ownership so annoying that people just throw in the towel.

                Comment

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