"Max" load for AR Comp and 123s

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  • StoneHendge
    Chieftain
    • May 2016
    • 2009

    "Max" load for AR Comp and 123s

    I want to work up a ladder with AR Comp and 123 Scenars for my new JP 22er but haven't seen any published data on the World Wide Web. XBR didn't give me much velocity before the accuracy node started widening. CFE 223 gave me some results to pursue further, but man that stuff is messy to work with.

    It appears like the low 28s is about as high as guys have gone, which would lead me to believe that 28.0 is around where a published max would be and the area to approach with caution, and that 26.0 would be a good starting point. I'm not chasing velocity - getting 2550 would be good enough for me (I'll of course take more without pushing the envelope). Will be using Lapua brass, GM205Ms and seating at 2.24

    Also wondering if anyone's tried AR Comp with 129/130s. I have a partial box of Accubond LRs gathering some dust and figure that since Alliant says AR Comp is good for heavies in 223 and 308, the same may hold for Grendel
    Let's go Brandon!
  • BluntForceTrauma
    Administrator
    • Feb 2011
    • 3897

    #2
    I think your analysis is correct. Start at 26.0 and work up to about 28.0, based on what I'm seeing here.
    :: 6.5 GRENDEL Deer and Targets :: 6mmARC Targets and Varmints and Deer :: 22 ARC Varmints and Targets

    :: I Drank the Water :: Revelation 21:6 ::

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    • COTNTOP
      Warrior
      • Mar 2011
      • 168

      #3
      28.0 works for me at mag length. Been a little higher but the best nodes seem to start around 27.5. Hope this helps

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      • Chazroh
        Bloodstained
        • Dec 2015
        • 88

        #4
        28.2arcomp with 123 amax at 2.260 gets 2595fps out of my 22" jp barrel

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        • shooter545
          Warrior
          • Aug 2012
          • 249

          #5
          I have excellent results with 28.0gr of AR Comp, 123gr SMK loaded to 2.260 out of my 20" AA and my 18" JP. I need to chrono it once I can get off the road working. Hopefully next weekend.

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          • Greg Skinner
            Unwashed
            • Aug 2016
            • 13

            #6
            I have a PF upper with a 18" Bartlein barrel, a AA Incursion upper (16" barrel) and a Kimber Montana converted to 6.5 G with a 22" barrel. AR-Comp does very well in all of these. 28.7 grains runs pretty well with 123 SMK and Amax in the AR's. The Kimber has a longer throat and magazine but still works well with 28.7 grains.

            I have been especially pleased with AR-Comp and 129 grain Hornady spire points. They shoot well out of all my Grendels and are consistent in accuracy - more so than any 123 grain bullets I have tried. Plus they are the cheapest hunting bullets available. I get about 2360 fps from both AR's and 2500 from the bolt, which makes them still moving faster than 1800 fps (Hornady's minimum threshold) at 300 yards. That's as far as I want to shoot deer sized game anyway, although I can get about 2300 fps using Nosler ABLR's - they are good to over 600 yds with their low threshold of expansion.

            The 123 grain loads are slightly compressed and the 129 are definitely compressed, but I have seen no ill effects from that. I vibrate them with an electric toothbrush so that it is a more consistent compression from round to round, and I have not noticed any particular pressure signs. I've got 4 or 5 loads from some of my Hornady and AA brass without having to discard any as a result of loose primer pockets.

            The 129 Hornady spire points have to be seated pretty deep (2.21 - 2.22) to clear the lands because of the shape of the ogive. Maybe that is why they are not so popular. That bothered me at first because it really crowds the powder space, but once I saw how well they shot I quit being bothered. At slightly over $24/100 I can do alot more shooting than I can with the more expensive match grade bullets, with as good or better accuracy.

            I use CCI 450 primers for all my loads, AA/Hornady brass for the AR's and Lapua brass for the bolt. OAL for the AR's is mag length or less.

            Standard loads

            AA Incursion 129gr Hornady SP, 26.9 AR-Comp, 2.21, 2360fps
            PF 129gr Hornady SP, 27.6 AR-Comp, 2.22, 2365fps
            Kimber bolt 129 Hornady SP 28.0 AR-Comp, 2.30, 2500fps

            These all average MOA pretty consistently if I do my part.

            Comment

            • BluntForceTrauma
              Administrator
              • Feb 2011
              • 3897

              #7
              Greg, great report, thanks!

              Shooter, lookin' forward to your chrono data.
              :: 6.5 GRENDEL Deer and Targets :: 6mmARC Targets and Varmints and Deer :: 22 ARC Varmints and Targets

              :: I Drank the Water :: Revelation 21:6 ::

              Comment

              • StoneHendge
                Chieftain
                • May 2016
                • 2009

                #8
                Thanks everyone! Looks like 26 to 28 will be the place to start. Hope to get some loaded up with the 123 Scenars sun/mon and too the range shortly thereafter. Will hopefully get to the 129 ABLRs soon took (I need to follow up on 123 scenar CFE loads and also play with the box of .308 175 gr RDFs that just arrived first).

                Interestingly, I checked Noslers load data for 123s vs. 129s and they have the same max charge for the powders they list for both bullet weights - except for RL15 where the max charge is actually larger for the 129s . Not going to push the envelope but AR Comp is allegedly a modernized/reformulated RL15. Based on Greg's results, a 22er with AR Comp might get some real interesting velocities for a bullet with a .285 G7. Looks like 26 to 28 should be the place to start there too.
                Let's go Brandon!

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                • vandiemenlander
                  Unwashed
                  • May 2017
                  • 5

                  #9
                  Any details on the Kimber Montana, Greg? That sounds like a neat project.

                  Comment

                  • Kilco
                    Chieftain
                    • Jan 2016
                    • 1201

                    #10
                    I've also been curious about AR-Comp. I've gotten amazing results with 8208 XBR, but if I can mimic the velocity and group size with less pressure, I'm on board.

                    Comment

                    • Greg Skinner
                      Unwashed
                      • Aug 2016
                      • 13

                      #11
                      Originally posted by vandiemenlander View Post
                      Any details on the Kimber Montana, Greg? That sounds like a neat project.
                      Yes, my gunsmith re-worked the bolt face for the 6.5 G and rebarreled with a Hart barrel (it was a 257 Roberts but I had a hard time finding brass). I wanted the true SAAMI chamber, but the reamer he got was the small diameter neck and the throat is longer. However, since I handload everything I have been able to come up with some pretty good loads and the magazine on the Kimber is long enough to seat the bullets out to wherever best accuracy is. I scoped it with a SWFA 5-20 on a rail with EGW rings. It is a very light rifle to begin with, but the scope is fairly heavy so finished weight is 8.4 lb. That is still pretty handy to carry and my old eyes appreciate the magnification. That 129 Hornady load with 28.0 gr of AR-Comp consistently shoots under 3/4 inch. The Nosler 129ABLR shoots about as well or better, but I have to hoard my supply because I have not been able to find them anywhere recently. The Montana does indeed make a fine 6.5 G bolt - no regrets on that conversion although the 257 Roberts did a fine job on deer through the years.

                      Comment

                      • grayfox
                        Chieftain
                        • Jan 2017
                        • 4295

                        #12
                        Originally posted by Greg Skinner View Post
                        Yes, my gunsmith re-worked the bolt face for the 6.5 G and rebarreled with a Hart barrel (it was a 257 Roberts but I had a hard time finding brass). I wanted the true SAAMI chamber, but the reamer he got was the small diameter neck and the throat is longer. However, since I handload everything I have been able to come up with some pretty good loads and the magazine on the Kimber is long enough to seat the bullets out to wherever best accuracy is. I scoped it with a SWFA 5-20 on a rail with EGW rings. It is a very light rifle to begin with, but the scope is fairly heavy so finished weight is 8.4 lb. That is still pretty handy to carry and my old eyes appreciate the magnification. That 129 Hornady load with 28.0 gr of AR-Comp consistently shoots under 3/4 inch. The Nosler 129ABLR shoots about as well or better, but I have to hoard my supply because I have not been able to find them anywhere recently. The Montana does indeed make a fine 6.5 G bolt - no regrets on that conversion although the 257 Roberts did a fine job on deer through the years.
                        Greg try Bruno's, I got some ABLRs from there couple weeks ago. Brunoshooters dotcom.
                        "Down the floor, out the door, Go Brandon Go!!!!!"

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                        • A.D.D. AR
                          Warrior
                          • Oct 2014
                          • 125

                          #13
                          guys- if you can't find them at Bruno's, try bullets.com sku# BL 11891. If it's one thing I'm good at, it's helping other people spend money! haha

                          -mike

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                          • 1911man
                            Warrior
                            • May 2015
                            • 482

                            #14
                            I have only used the 123 Amax/ELD but I have used AR Comps successfully in 3 barrels now and each of them found an accuracy node between 27.9 and 28.3 grains. I only have chronograph data for my 18" BHW barrel but it averages 2500 fps and SDs under 10 fps with 28.3 grains. I always start at 27.0 grains and have loaded the 123 ELD as high as 28.5 grains. I stopped because I started losing accuracy at that point and the case gets very full at that point. You have to vibrate the cases to get a bullet to seat at that high of a charge. I wasnt seeing any pressure signs though. I have never tried the heavier bullets because the AR Comp/123 ELD combo works so good. This is definitely my go to powder for Grendel. I also use it with a 168 ELD in 308 and get good velocity and low SDs.

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                            • Greg Skinner
                              Unwashed
                              • Aug 2016
                              • 13

                              #15
                              Thanks for the tips on the ABLR sources. I usually use Powder Valley, but they have not had any for quite some time. I just got some from Third Gen on a private message tip. I'll just hoard them since I have good loads worked up. They shoot exceptionally well out of the Kimber. I ran a ladder from 27.0 to 27.8 in 0.1 increments with AR-Comp and they all shot inside a 1.09" group at 106 yd. with an overall velocity spread from 2473 to 2519. I seated them long, though - 2.42 oal, which is 0.02 off the lands. Node seemed to be at 27.2 with a velocity of 2480 all in one ragged hole.

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