FInally made it to the range

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  • FInally made it to the range

    OK, went to the range today with the new Grendel I built with the 18" barrel from here on the board that John is selling.

    Well my fireforming loads, IMI brass, 23.5gr H4198 and .263 dia 87gr Speer hollow point, yes .263 not .264, I have a bunch of these that I ran across cheap. Well the largest group was .730 w x .515 h smallest was .765 w x .310 h, not bad I thought, so I break out the Hornady 123gr A-Max factory loads.... Well that was a real puzzler for me... .290 w x 1.695 h and .980 w x 2.230 h... OK any idea why the nice fancy factory loads string vertically like that and the funky fireforming loads shoot so well at 100yds???

    I am not sure what to think about it, any ideas as to why it would do that besides sun spots, solar winds etc.....


    Greg
  • LR1955
    Super Moderator
    • Mar 2011
    • 3355

    #2
    Originally posted by GregP42 View Post
    OK, went to the range today with the new Grendel I built with the 18" barrel from here on the board that John is selling.

    Well my fireforming loads, IMI brass, 23.5gr H4198 and .263 dia 87gr Speer hollow point, yes .263 not .264, I have a bunch of these that I ran across cheap. Well the largest group was .730 w x .515 h smallest was .765 w x .310 h, not bad I thought, so I break out the Hornady 123gr A-Max factory loads.... Well that was a real puzzler for me... .290 w x 1.695 h and .980 w x 2.230 h... OK any idea why the nice fancy factory loads string vertically like that and the funky fireforming loads shoot so well at 100yds???

    I am not sure what to think about it, any ideas as to why it would do that besides sun spots, solar winds etc.....


    Greg
    Greg:

    Most probable is two fold. First, the 123 AMAX are giving your more recoil and unless you have a very consistent and pretty solid hold is more prone to vertical stringing. Also, some of it is probably due to yaw from the secant ogive or hybrid tangent / secant ogive on the 123 AMAX. The 123 AMAX bullet is more intended for longer distances -- at least 300 where its profile gives it an edge over the more rounded tangent or maybe even round nose ogive.

    Now you see why bench rest shooters use flat base bullets with tangent ogives and not boat tail bullets with VLD ogives.

    LR1955

    Comment


    • #3
      Originally posted by LR1955 View Post
      Greg:

      Most probable is two fold. First, the 123 AMAX are giving your more recoil and unless you have a very consistent and pretty solid hold is more prone to vertical stringing. Also, some of it is probably due to yaw from the secant ogive or hybrid tangent / secant ogive on the 123 AMAX. The 123 AMAX bullet is more intended for longer distances -- at least 300 where its profile gives it an edge over the more rounded tangent or maybe even round nose ogive.

      Now you see why bench rest shooters use flat base bullets with tangent ogives and not boat tail bullets with VLD ogives.

      LR1955
      Does that mean I shouldn't use hornady 123 a-max to zero my new upper(when it comes). All I have to get started is 123 a-max(es).

      Comment


      • #4
        LR,

        I thought about the yawing, but thought it wouldn't be that bad, with my 6.5x284 it is just fine at 100 all the way out to 600 with the 120gr A-Max. As for the rest, I was using both front rest and a rear bag. I shot my .17 also just to make sure it wasn't me and shot a couple of .190 to .270 groups with it so I am just not sure what it was doing. Normally when I have vertical strings my velocity is all over the place, but I am not sure as I did not take the chronograph with me since it was mostly fireforming and get the scope zeroed in today. I will have to pick up another box of the 123gr to test them at 300 and see what they do there. I had not thought about them not working at 100yds, but I guess that could be the reason.

        Greg

        Comment


        • #5
          Were you loading your shots one at a time of by the mag load? In the latter case, the gun gets lighter and the balance shifts with each shot. I realize we're only talking maybe an ounce at a crack. Just throwing it out there. Do you shoot it loose and let it dictate the various planes of movement? Do you hold it in a death grip and try to minimize any rhythm it generates? Benchrest front, bipod front, whatever you can find at the range front? Rear bag, rear monopoint, the bench, your arm?

          The point of all those is when testing loads for patterns of behavior, if you're not shooting a lead sled or equivalent, you introduce all kinds of variables that are not necessarily indicative of the load's actual behavior. Once you get a load down pat, minus the personal influences, then introduce how you play into it's outcome.

          Otherwise, it's like everyone in the orchestra trying to get in tune at the same time.

          That having been said. It's a lot more fun to throw all the ingredients into the pot and just enjoy cooking. Unfortunately, every recipe comes out like stew.

          Hoot

          Comment


          • #6
            Originally posted by Hoot View Post
            Were you loading your shots one at a time of by the mag load? In the latter case, the gun gets lighter and the balance shifts with each shot. I realize we're only talking maybe an ounce at a crack. Just throwing it out there. Do you shoot it loose and let it dictate the various planes of movement? Do you hold it in a death grip and try to minimize any rhythm it generates? Benchrest front, bipod front, whatever you can find at the range front? Rear bag, rear monopoint, the bench, your arm?

            The point of all those is when testing loads for patterns of behavior, if you're not shooting a lead sled or equivalent, you introduce all kinds of variables that are not necessarily indicative of the load's actual behavior. Once you get a load down pat, minus the personal influences, then introduce how you play into it's outcome.

            Otherwise, it's like everyone in the orchestra trying to get in tune at the same time.

            That having been said. It's a lot more fun to throw all the ingredients into the pot and just enjoy cooking. Unfortunately, every recipe comes out like stew.

            Hoot

            Hoot,

            I was using a benchrest front support with lead shot filled bag on it, and a benchrest rear bag. Loose grip, and just enough cheek weld to take the slack out of the skin. Single loading for two strings, then 5 shots from the mag for the last group. The fireforming loads were all fired from the mag 5 per string. Gasblock is adjusted down to just get the bolt to lock back then 1/8 turn more so I am probably under gassed as it were. But those were all good questions that I did not supply the data for. I still need to work on the trigger as there is a rough spot in the second stage right now, I didn't want to make it too light or work it over like my bolt guns, they are all set at about 8oz. This one is about 4 1/2 pounds so that might be a factor also. I did not have a break on the rifle yet as I have not ordered one, I am still thinking about getting the Ross, but not sure right now.

            I would be happy with stew as long as it was round and not strung out vertically!

            Greg

            Comment


            • #7
              PM inbound Greg

              Comment

              • LR1955
                Super Moderator
                • Mar 2011
                • 3355

                #8
                Originally posted by davidj View Post
                Does that mean I shouldn't use hornady 123 a-max to zero my new upper(when it comes). All I have to get started is 123 a-max(es).
                Dave:

                Sure can. Just use a consistent and solid hold on the rifle when you blast from a bench. Also note that your zero with your Hornday loads will probably not hold with different loads, even though they may not seem too far apart at 100 yards.

                The problem here most likely isn't the load coming from Hornady but the shooters position, firing technique, and attentional focus through his string.

                LR1955

                Comment

                • LR1955
                  Super Moderator
                  • Mar 2011
                  • 3355

                  #9
                  Originally posted by GregP42 View Post
                  Hoot,

                  I was using a benchrest front support with lead shot filled bag on it, and a benchrest rear bag. Loose grip, and just enough cheek weld to take the slack out of the skin. Single loading for two strings, then 5 shots from the mag for the last group. The fireforming loads were all fired from the mag 5 per string. Gasblock is adjusted down to just get the bolt to lock back then 1/8 turn more so I am probably under gassed as it were. But those were all good questions that I did not supply the data for. I still need to work on the trigger as there is a rough spot in the second stage right now, I didn't want to make it too light or work it over like my bolt guns, they are all set at about 8oz. This one is about 4 1/2 pounds so that might be a factor also. I did not have a break on the rifle yet as I have not ordered one, I am still thinking about getting the Ross, but not sure right now.

                  I would be happy with stew as long as it was round and not strung out vertically!

                  Greg
                  Greg:

                  Sorry but the most likely cause is your position, firing process, and attentional focus. Yaw may have something to do with it but probably not much -- just like I said in my post.

                  This on has nothing to do with the gas block, trigger, whose brand of rest or sand bags you use, the type of sand used in the bags, whether or not you put baby powder on your bags, velocity spreads (particularly at 100 yards), etc. Guys always try to find the most complex reasons for simple things. And no, you don't have to neck turn the brass, anneal it, weigh individual charges, measure ogives on bullets, or even measure bullet weights.

                  Letting a service type of rifle free recoil as you are doing is a sure way to see your groups string vertical. Your lighter bullets didn't string as much because the recoil with them was much lighter. The AMAX bullets probably gave you 30 - 40 % more recoil and you strung vertically because you were using bench rest techniques to shoot a gas operated AR-15.

                  So, next time set up your firing position based on your ability to easily see a sight picture with your head held in a natural position and with you being in total control of the rifle. Adjust your seat, sand bags, rest etc so the rifle fits you perfectly. Shoot strings while maintaining your attention on sight picture through the entire shot and until you re-index the target.

                  LR1955

                  Comment


                  • #10
                    Originally posted by LR1955 View Post
                    Greg:

                    Sorry but the most likely cause is your position, firing process, and attentional focus. Yaw may have something to do with it but probably not much -- just like I said in my post.

                    This on has nothing to do with the gas block, trigger, whose brand of rest or sand bags you use, the type of sand used in the bags, whether or not you put baby powder on your bags, velocity spreads (particularly at 100 yards), etc. Guys always try to find the most complex reasons for simple things. And no, you don't have to neck turn the brass, anneal it, weigh individual charges, measure ogives on bullets, or even measure bullet weights.

                    Letting a service type of rifle free recoil as you are doing is a sure way to see your groups string vertical. Your lighter bullets didn't string as much because the recoil with them was much lighter. The AMAX bullets probably gave you 30 - 40 % more recoil and you strung vertically because you were using bench rest techniques to shoot a gas operated AR-15.

                    So, next time set up your firing position based on your ability to easily see a sight picture with your head held in a natural position and with you being in total control of the rifle. Adjust your seat, sand bags, rest etc so the rifle fits you perfectly. Shoot strings while maintaining your attention on sight picture through the entire shot and until you re-index the target.

                    LR1955
                    LR,

                    I did not know there was that much difference in a gas operated weapon, I have been shooting bolt guns and single shots for so long that I didn't even think about it. So a gas operated firearm needs a firmer grip shooting from the bench? Is there a different technique needed to shoot an AR style weapon, if so I might be screwing that up as I am using the same as if I was shooting a bench match. Any tips you have would be great.

                    Thanks,
                    Greg

                    Comment

                    • LR1955
                      Super Moderator
                      • Mar 2011
                      • 3355

                      #11
                      Originally posted by GregP42 View Post
                      LR,

                      I did not know there was that much difference in a gas operated weapon, I have been shooting bolt guns and single shots for so long that I didn't even think about it. So a gas operated firearm needs a firmer grip shooting from the bench? Is there a different technique needed to shoot an AR style weapon, if so I might be screwing that up as I am using the same as if I was shooting a bench match. Any tips you have would be great.

                      Thanks,
                      Greg
                      Greg:

                      Strong position, solid hold. Not vice-like but pretty solid none the less. When you set up your bench rest position, set it up to fit you and set it up so the barrel is oriented pretty much into the middle of the target. The key is that the position fits you in a manner where you have a-lot of confidence that you can take five shots sustained fire without the recoil blowing you out of position.

                      Take the five shots sustained fire, attention focused on sight picture throughout the entire shot until you re-index for the next shot. Five shots in about fifteen or twenty seconds ought to be about right.

                      LR1955

                      Comment


                      • #12
                        Originally posted by LR1955 View Post
                        Greg:

                        Strong position, solid hold. Not vice-like but pretty solid none the less. When you set up your bench rest position, set it up to fit you and set it up so the barrel is oriented pretty much into the middle of the target. The key is that the position fits you in a manner where you have a-lot of confidence that you can take five shots sustained fire without the recoil blowing you out of position.

                        Take the five shots sustained fire, attention focused on sight picture throughout the entire shot until you re-index for the next shot. Five shots in about fifteen or twenty seconds ought to be about right.

                        LR1955
                        LR,

                        Thanks, I am planning on heading out to the range tomorrow (If it doesn't rain here) and I will try that out. Like I said I am so used to BR shooting and letting the rifle free recoil that I hadn't thought about what it would do to an AR type weapon. I will see if I can get 5 aimed shots off in that time frame, it might be something I have to work on as to me that is fast shooting

                        Greg

                        Comment

                        • LR1955
                          Super Moderator
                          • Mar 2011
                          • 3355

                          #13
                          Originally posted by GregP42 View Post
                          LR,

                          Thanks, I am planning on heading out to the range tomorrow (If it doesn't rain here) and I will try that out. Like I said I am so used to BR shooting and letting the rifle free recoil that I hadn't thought about what it would do to an AR type weapon. I will see if I can get 5 aimed shots off in that time frame, it might be something I have to work on as to me that is fast shooting
                          Greg
                          Greg:

                          One of the issues is the friction between the forend, stock, and the bags. The irregular and sometimes sharp edges on the forend hook and catch on bags so they won't slide back consistently. And the recoil is much higher due to the stock design, rifle weight, and cartridge being fired.

                          Guys who want to shoot bench with an AR buy aluminum sled things that they fit onto the forend and stock to allow the rifle to slide. They also have bags that fit the sleds. Even then my bet is that the higher recoiling Grendel compared to the various 6 mm cartridges still gives them problems. Since you shoot BR, look up these aluminum sleds for AR's as they may be of interest to you.

                          The time frame is realistic but not necessarily set in stone. However, every BR match I have seen showed those guys frantically working bolts to get their strings off very quickly once their flags showed them something consistent. Five shots in twenty or thirty seconds doesn't seem to be too uncommon with the BR crowd either. Its is just that their attention doesn't need to be focused on a sight picture throughout their shooting process. They check flags, optic, then pull trigger, work bolt, reload, check flags, optic, shoot again, etc.

                          If you think you can, you are right. If you think you can't, you're still right.

                          Comment


                          • #14
                            LR,

                            I used a firmer grip on the rifle this time, IE hold the front of the magwell and didn't let it free recoil like I had been. The 123 A-Max shot much better this time, just over 1 inch, but at 200 they went just over 1.4 inches. Yes, the float tube on mine is knurled, so I was resting it on the last two inches that are smooth. If I can get it to shoot 1/2 moa consitantly I will be more than happy with it. Thanks for the tips.

                            Greg

                            Comment

                            • LR1955
                              Super Moderator
                              • Mar 2011
                              • 3355

                              #15
                              Originally posted by GregP42 View Post
                              LR,

                              I used a firmer grip on the rifle this time, IE hold the front of the magwell and didn't let it free recoil like I had been. The 123 A-Max shot much better this time, just over 1 inch, but at 200 they went just over 1.4 inches. Yes, the float tube on mine is knurled, so I was resting it on the last two inches that are smooth. If I can get it to shoot 1/2 moa consitantly I will be more than happy with it. Thanks for the tips.

                              Greg
                              Greg:

                              1/2 minute consistently is asking a bit too much. If you are getting 3/4 minute with factory loads consistently like you did at 200, you and the rifle and the ammo are doing just fine.

                              As you can see, a different mindset with a gas gun that is essentially a service rifle is in order to include its capabilities. If a factory Grendel firing factory loads holds under a minute consistently, you have a great combination. It is marginally competitive in High Power but is a good bet for the action sports where you shoot steel on field fire courses and it is a good hunting combination as well.

                              LR1955

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