Barrel Length Query

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  • 1750Shooter
    Unwashed
    • Feb 2015
    • 23

    Barrel Length Query

    Gun club just setup a 1000 yd. range & we are going to be starting to shoot LR silhouette. I'm going to try to use my 18" Grendel AR for starters, but was wondering of going to a 24" barrel would be any help. Thanks for any input.
  • CPT.CRAZY
    Warrior
    • Feb 2012
    • 244

    #2
    I've shot my 18" out to 1200 yrds, but IMHO a longer barrel will make a difference if yiu are fighting any cross wind.
    sigpic

    Comment

    • LR1955
      Super Moderator
      • Mar 2011
      • 3355

      #3
      Originally posted by 1750Shooter View Post
      Gun club just setup a 1000 yd. range & we are going to be starting to shoot LR silhouette. I'm going to try to use my 18" Grendel AR for starters, but was wondering of going to a 24" barrel would be any help. Thanks for any input.
      Since you will be using an optic, and given the ballistics of a 2500 fps or less bullet, and that you said you would use your 18" Grendel 'for starters', just use what you have and if you are happy then keep using it. The extra 50 fps or so you may get from a 24" barrel is something you probably can't measure and the longer barrel may give you more balance problems when shooting standing.

      For any of the shooting sports, use what you have for starters while seeing what equipment works and what doesn't. Then spend money.

      Remember that in the shooting sports, the easiest point you can make is the one you buy.

      LR55

      Comment

      • LRRPF52
        Super Moderator
        • Sep 2014
        • 8569

        #4
        What altitude is this range at?
        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

        • 1750Shooter
          Unwashed
          • Feb 2015
          • 23

          #5
          Originally posted by LRRPF52 View Post
          What altitude is this range at?
          About 5500'

          Comment

          • LRRPF52
            Super Moderator
            • Sep 2014
            • 8569

            #6
            You'll be fine with 18". Your station pressure is probably going to average ~24.4" Hg. The 18" will push 123gr supersonic well past 1400yds at that altitude.

            Using the Litz G7 BC for the 123gr SMK (.260), you'll still be supersonic at 1450yds starting with a 2500fps mv. Your difference in drop at 1000yds between an 18" and 24" will be .8 Mils. Wind deflection difference will be .1 Mils.

            Buy lots of ammo, and go shoot that bad boy.
            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

            • NugginFutz
              Chieftain
              • Aug 2013
              • 2622

              #7
              I recently shot some proof loads in both my 18" BHW and 22" BHW. I shot the 123 AMAx through both, with CFE223 and IMR8208XBR. The 31.5 gr of CFE drove the 123 through the 18" barrel at 2509 fps, whereas the 22" barrel achieved 2647 fps. With 28.0 gr of 8208, the results were 2409 fps for the 18" and 2524 fps for the 22" barrel.

              Code:
              Temp	Powder		Charge	18"	22"	Diff
              					
              81 'F	CFE 223		31.5	2509	2647	138
              81 'F	IMR 8208 XBR	28.0	2409.2	2524.4	115.2
              With the CFE 223, I had a little more headroom, but ES was degrading. As with the CFE, I had some additional headroom with the 8208, but OCW workups showed no reason to go any higher.

              Long and short of it is that Apples:Apples, the 4" of difference the two barrels gave me an average increase of 126 fps. Extrapolating, another 2" for the 24" barrel, it could offer an additional 60 fps, for a net of ~185 fps.

              Also, it looks as if the CFE benefited from the additional length more than the 8208 did. I suspect that this had something to do with the 8208 burning faster than the CFE, but I have no other data to support this hypothesis.

              So, should your shooting abilities exceed the reach of your current 18" setup, it looks to me like an additional 4-6" of barrel can up your MV between 115 - 207 fps (using the above loads as a baseline).
              If it's true that we are here to help others, then what exactly are the others here for?

              Comment

              • biodsl
                Chieftain
                • Aug 2011
                • 1714

                #8
                Originally posted by NugginFutz View Post
                I recently shot some proof loads in both my 18" BHW and 22" BHW. I shot the 123 AMAx through both, with CFE223 and IMR8208XBR. The 31.5 gr of CFE drove the 123 through the 18" barrel at 2509 fps, whereas the 22" barrel achieved 2647 fps. With 28.0 gr of 8208, the results were 2409 fps for the 18" and 2524 fps for the 22" barrel. (SNIP) Long and short of it is that Apples:Apples, the 4" of difference the two barrels gave me an average increase of 126 fps. Extrapolating, another 2" for the 24" barrel, it could offer an additional 60 fps, for a net of ~185 fps.
                I'm pretty impressed with these numbers. They significantly exceed the general 20-24 fps per inch guideline. Not to totally hi-jack this thread, I'd be interested in hearing from other BHW 22" owners (I think there are a few) if they achieving similar velocities. 31.2 grains of CFE behind the 123 grain AMax is only netting me 2468 fps out of a 20" Lilja. Elevation is essentially sea-level.
                Paul Peloquin

                Did government credibility die of Covid or with Covid?

                Comment

                • NugginFutz
                  Chieftain
                  • Aug 2013
                  • 2622

                  #9
                  Originally posted by biodsl View Post
                  ... 31.2 grains of CFE behind the 123 grain AMax is only netting me 2468 fps out of a 20" Lilja.
                  In the same series, I ran 31.2 gr of CFE through the 18" BHW and averaged 2488.8 fps with the 123 Amax. The BHW's do tend to run faster MV's for the same recipes. I believe it was GLShooter who said that the BHW P3's were essentially like getting an extra 2" of barrel.

                  Originally posted by biodsl View Post
                  ... Elevation is essentially sea-level.
                  At the muzzle, it really doesn't make any difference.
                  Last edited by NugginFutz; 09-11-2015, 04:17 AM.
                  If it's true that we are here to help others, then what exactly are the others here for?

                  Comment

                  • 208Grendel
                    Unwashed
                    • May 2015
                    • 9

                    #10
                    Originally posted by biodsl View Post
                    I'm pretty impressed with these numbers. They significantly exceed the general 20-24 fps per inch guideline. Not to totally hi-jack this thread, I'd be interested in hearing from other BHW 22" owners (I think there are a few) if they achieving similar velocities. 31.2 grains of CFE behind the 123 grain AMax is only netting me 2468 fps out of a 20" Lilja. Elevation is essentially sea-level.
                    I'm pushing a 123 gr AMAX through a 22" BHW 1x8 twist at an average of 2,456 fps with 30.6 gr of CFE223. Elevation = approx. 2700 ft.

                    Comment

                    • SG4247
                      Warrior
                      • Aug 2013
                      • 497

                      #11
                      For that type of shooting i would say 22".

                      I say 22" for both weight and MV in Grendel.

                      Personally, I always struggle with the 18" for long range. I have shot several and find them generally to be too light weight overall and too short making it difficult to keep steady on the rest or bags. They are very sensitive to trigger pull weight which is critical. My shortest AR long gun is 20" with weight added to the stock. The others are all 22"-26".

                      You have to be a really good to manage a short light barrel in the long game.

                      So the next question is barrel diameter...
                      NRA F-Class Mid Range High Master

                      Comment

                      • Grendelseeker
                        Bloodstained
                        • Jul 2016
                        • 64

                        #12
                        Originally posted by NugginFutz View Post
                        In the same series, I ran 31.2 gr of CFE through the 18" BHW and averaged 2488.8 fps with the 123 Amax. The BHW's do tend to run faster MV's for the same recipes. I believe it was GLShooter who said that the BHW P3's were essentially like getting an extra 2" of barrel.
                        2 questions-
                        What kind of chrono are you using that gives you .decimal accuracy/readouts?? The doppler radar one? Or is this just a product of averaging odd numbers?

                        BHW's site does not show any 6.5G barrels. What's up with that? Are we still in Grendeland here?

                        Comment

                        • terrywick4
                          Warrior
                          • Sep 2014
                          • 181

                          #13
                          Originally posted by Grendelseeker View Post
                          2 questions-
                          What kind of chrono are you using that gives you .decimal accuracy/readouts?? The doppler radar one? Or is this just a product of averaging odd numbers?

                          BHW's site does not show any 6.5G barrels. What's up with that? Are we still in Grendeland here?
                          BHW uses 264 LBC I think

                          Comment

                          • NugginFutz
                            Chieftain
                            • Aug 2013
                            • 2622

                            #14
                            Originally posted by Grendelseeker View Post
                            2 questions-
                            What kind of chrono are you using that gives you .decimal accuracy/readouts?? The doppler radar one? Or is this just a product of averaging odd numbers?

                            BHW's site does not show any 6.5G barrels. What's up with that? Are we still in Grendeland here?
                            My chronographs both read to the nearest fps (neither is the LabRadar). The decimal cited in that post was simply the average of the shot string(s), carried to the nearest 1/10th.


                            Originally posted by terrywick4 View Post
                            BHW uses 264 LBC I think
                            Correct. While they had a limited run of SAAMI 6.5 Grendel chambers, they've now gone back to exclusively chambering the .264LBC.
                            If it's true that we are here to help others, then what exactly are the others here for?

                            Comment

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