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  • Gunfighter25

    This is getting interesting...

    Just checked my chamber with the Hornady Lock-N-Load OAL and the 6.5 Grendel modified round with a Barnes TSX 120 grain - 2.360" average for five measurements. Using the load table that came with my Lee dies, the recommended OAL for the Barnes 120 TSX was 2.230".

    My math might be a little rusty but that comes out to a jump of 0.130". Bullet seats with the first ring showing at 2.235" OAL and is not compressing a 30.9 grain load of BLC2. Anyone else thinks this is a little excessive jump for an AR-15 chamber? I double checked the headspace again -still within spec, Go-gauge closes and locks, No-go gauge doesn't close or locks. Test rounds will chamber and lock by pushing the bolt close.

    The loads I'm going to test are AA cases, FL sized with a Redding die, primed with CCI 450 small rifle primers, the Barnes 120 grain TSX and BLC2 loads of 29.7, 30.4 and 30.9 using the recommended loads from the Lee load table of 29.7 grains to 30.8 grains. Just checked the old loads posted on this forum but they don't list the OAL but my loads are on the lighter end (max at 31.5 gr BLC2).

    In another thread I had good results with the Nosler Partition and Sierra Pro Hunters seating to 2.250" but even that is a jump of 0.110". At this point, I'm inclined to go with what works unless some body has another thing I need to check?

    Gunfighter
  • LR1955
    Super Moderator
    • Mar 2011
    • 3355

    #2
    Originally posted by Gunfighter25 View Post
    Just checked my chamber with the Hornady Lock-N-Load OAL and the 6.5 Grendel modified round with a Barnes TSX 120 grain - 2.360" average for five measurements. Using the load table that came with my Lee dies, the recommended OAL for the Barnes 120 TSX was 2.230".

    My math might be a little rusty but that comes out to a jump of 0.130". Bullet seats with the first ring showing at 2.235" OAL and is not compressing a 30.9 grain load of BLC2. Anyone else thinks this is a little excessive jump for an AR-15 chamber? I double checked the headspace again -still within spec, Go-gauge closes and locks, No-go gauge doesn't close or locks. Test rounds will chamber and lock by pushing the bolt close.

    The loads I'm going to test are AA cases, FL sized with a Redding die, primed with CCI 450 small rifle primers, the Barnes 120 grain TSX and BLC2 loads of 29.7, 30.4 and 30.9 using the recommended loads from the Lee load table of 29.7 grains to 30.8 grains. Just checked the old loads posted on this forum but they don't list the OAL but my loads are on the lighter end (max at 31.5 gr BLC2).

    In another thread I had good results with the Nosler Partition and Sierra Pro Hunters seating to 2.250" but even that is a jump of 0.110". At this point, I'm inclined to go with what works unless some body has another thing I need to check?

    Gunfighter
    GF:

    Go with what works. If you want, seat the bullet out farther providing you can and still have sufficient neck tension for all the banging around a cartridge gets with a gas operated rifle. There is nothing dangerous about seating a bullet farther out than what is printed in a manual. There may be danger if you end up seating it so far out that it really needs to be jammed into the rifling for the bolt to go into battery.

    An AR-15 is not a bolt action rifle and a bolt action hunting rifle isn't a match rifle, which isn't a bench rest rifle. And so on.

    LR1955

    Comment


    • #3
      Gunfighter,
      For OAL you need to measure for each bullet. You're OAL for the Barnes will not be the same as the Nolser or Sierra because of different ogives and bullet profiles.

      I posted this with my chamber measuring findings,
      So, here the problem, I made a cartridge length measuring device to measure how deep the throat is cut in my chamber but I'm getting different measurements with different bullets. I'm using Hornady's Lock-N-Load Comparator to measure to the ogive, not overall length. Shouldn't the dimension from the bolt face to where the
      Last edited by Guest; 01-14-2012, 04:14 PM.

      Comment


      • #4
        I have a .264 lbc-ar chamber and using the Hornady Lock and Load OAL tool with the same bullet my measurements were 2.290", 2.292", and 2.289".

        The loads I have been working with for the 120gr tsx have been set to the OAL recommended by the load data on the Hodgdon web site of 2.200". Thats a bigger jump than what the Barnes recommends. However, I've gotten a few groups with 3 shots touching.

        I agree with the previous advice. Go with what works. We are limited by magazine length anyway so it may not be always possible to get the jump we want.

        Brian

        Comment

        • rasp65
          Warrior
          • Mar 2011
          • 660

          #5
          Barnes recommends a jump of .010"

          Comment


          • #6
            Manufacturer load data tables are based on SAAMI specs and are always on the conservative side for liability reasons. But like others said, go with what works.

            Comment


            • #7
              Some guns shoot really poorly at .010 off the lands, and will shoot really well at .030 off or some other jump length. There is no rule until you get to VLD's and then they shoot best jammed or jumped a lot.
              Bob

              Comment

              • sneaky one
                Chieftain
                • Mar 2011
                • 3077

                #8
                I tried the 120 TSX 2 yrs. ago, at 2.235,and 2.260-both oals. shot great. I contacted barnes in 2010 and they said .030-.050-off should be best . After measuring seating depths my specs were very close to gunfighters. The tsx is easier to load than the ttsx-with that one, I loaded it to 2.31 oal.- it is .030-off- and redid the tip to run thru the mag. It shot fine, opened up perfectly- thru the H2O jugs- great close in round. Every bullet is different, even from the same box / batch ! OAL. Trials will get you the results you seek. Barnes seem to shoot best-soft loaded, don't seek max. charge.

                Comment


                • #9
                  Barnes recommends a 0.050" setback.

                  Comment

                  • Gunfighter25

                    #10
                    Thanks guys. Feeling a little better about the big jump to the lands. Plan now is to test the powder charges, holding 2.235" OAL, look for the smallest group, tweak the powder charges until I get a consistant group, then chronograph so I know what the MV is. Goal is to get a hunting load for this bullet, 1.5" at 100 yards is good. Anything smaller than that is gravy. If I need a round with a smaller group at longer than 300 yards, I've can use the Partition, Pro Hunter and AMAX loads, all 0.5 MOA.

                    Comment


                    • #11
                      1.5" is not that good, I prefer mine do .5-.75" at 100yds, or better.

                      Comment

                      • Gunfighter25

                        #12
                        D - 1.5 inches at 100 yards is more than adequate accuracy considering the last wild pig I shot at was at three feet, quartering to the right, going uphill and accellerating. Almost kicked him first but he broke cover just as I was entering the brushy area. Snapped off two shots almost straight down and saw the pig jump when he hit hyperdrive. Checked the area but no blood. The longest hit to date was 75 yards, uphill at about 30 degrees, also in heavy cover. Lava rock is a bitch to climb after a kill. Tore up my boots and gloves - they don't call it A'A lava for nothing.

                        Anyway, we have a winner. 31.5 grains BLC2 behind the TSX - 0.60 to 0.70 at 100 yards. First two shot cut nice round holes but the last three of the string of five still was keyholing at 29.7 grains. At 30.3 grains most shots were cut round but had one keyhole (#4 shot) and was about three inches across the target (three inch diamond black at 100 yards). 30.9 was about the same. The 31.0 load was a little tighter, no keyholes and the 31.5 load had the first two touching with the rest stringing to the right and up. Primers were slightly flattened but no cratering. Calling this good.

                        Wind was from the east at gusty 10-15 mph. Temp was 78 degrees and overcast. Target was backlit from the sun.

                        Next step will be to keep the load charge constant and vary the seating depth to see if it makes a difference.

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