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Barrel Length - Powder Burn

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  • Barrel Length - Powder Burn

    https://www.classicfirearms.com/vide...tent=Secondary

  • #2
    The only thing that pulled up was a video about the 223 versus the black out

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    • #3
      Originally posted by Ernie View Post
      The only thing that pulled up was a video about the 223 versus the black out
      he winds up comparing powder burn

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      • #4
        His conclusions on barrel lengths?

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        • #5
          Originally posted by Ernie View Post
          His conclusions on barrel lengths?
          Ernie, the video was just an opinion piece with no actual measurements. There's a lot of misinformation concerning the .300 Blackout. Often, you will see people say that all the powder is burned in the first 9 inches of barrel. Some think it's worthless to have a longer barrel.

          I found a video where the velocity was measured for various barrel lengths. I'm comforted to know that my 16-inch barrel produces 200 fps more than what I would have gotten from a 9-inch. So far, I've killed 4 whitetail with mine. Two with subsonic ammo and two with supersonic. Suppressed.

          https://www.youtube.com/watch?v=4VNl7QXykUY

          Click image for larger version  Name:	300BLK Barrel Length.JPG Views:	0 Size:	32.0 KB ID:	761053

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          • #6
            Originally posted by PigHunter View Post

            Ernie, the video was just an opinion piece with no actual measurements. There's a lot of misinformation concerning the .300 Blackout. Often, you will see people say that all the powder is burned in the first 9 inches of barrel. Some think it's worthless to have a longer barrel.

            I found a video where the velocity was measured for various barrel lengths. I'm comforted to know that my 16-inch barrel produces 200 fps more than what I would have gotten from a 9-inch. So far, I've killed 4 whitetail with mine. Two with subsonic ammo and two with supersonic. Suppressed.

            https://www.youtube.com/watch?v=4VNl7QXykUY

            Click image for larger version Name:	300BLK Barrel Length.JPG Views:	0 Size:	32.0 KB ID:	761053
            That is only half of it, you have to consider the various powders that can be used.
            I thought it interesting the cans got hot - I did not know that. Also, gas coming back into the shooters face ?? I did not see that with the M-16.
            I would like to see some paper targets from the two weapons, or are they just considered spray and pray.

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            • #7
              Originally posted by jhjimbo View Post

              That is only half of it, you have to consider the various powders that can be used.
              I thought it interesting the cans got hot - I did not know that. Also, gas coming back into the shooters face ?? I did not see that with the M-16.
              I would like to see some paper targets from the two weapons, or are they just considered spray and pray.
              Jim, that's a good point. I've used my suppressor mainly on the .300 BLK and the 6.5 CM. There was only minor heating but I wasn't shooting as fast as the guy in the video.

              As far as gas blowback, I've noticed that a little on the 5.56 but haven't on the .300 BLK.

              I'm getting 1.25-inch 3-shot groups with my handloaded 110gr Hornadys.
              Last edited by PigHunter; 11-25-2020, 12:35 AM.

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              • #8
                Originally posted by PigHunter View Post

                Jim, that's a good point. I've used my suppressor mainly on the .300 BLK and the 6.5 CM. There was only minor heating but I wasn't shooting as fast as the guy in the video.

                As far as gas blowback, I've noticed that a little on the 5.56 but haven't on the .300 BLK.

                I'm getting 1.25-inch 3-shot groups with my handloaded 110gr Hornadys.
                110gr would be the .300? is it a AR type 16" barrel? How does the 5.56 do?

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                • #9
                  Originally posted by jhjimbo View Post

                  110gr would be the .300? is it a AR type 16" barrel? How does the 5.56 do?
                  Yep, the 110gr is for the 300BLK. I made a mistake in my previous post. It's actually a Barnes bullet. My load is 19.6 grains of W296. Here's the official load sheet. I haven't measured it with the chronograph.

                  Click image for larger version

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                  The barrel is 16-inch stainless and I installed it on a completed upper. Here's a pic with the suppressor attached.

                  Click image for larger version

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                  My 5.56 upper stays in the safe and it's been a couple of years since I've used it. I'm concerned about accidently chambering a .300 BLK round in that smaller chamber. So, I never take both calibers to the range on the same day. Three years ago it produced an half-inch three shot group with factory loaded Remington 55g PSPs.

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                  • #10
                    I shoot pretty long barrels most of the time because I typically want the highest velocity a given cartridge can deliver. I hate to shoot a 25-06 or any magnum with a barrel less than 26". I am occasionally limited by weight restrictions in competition. For example in F-Class Open competition, I can shoot a 30" to 32" 1.25" no-taper barrel within the 22 pound weight class. In the F-TR (military rounds -.308 & .223) I have to switch to a Palma contour barrel to make the 18 pound weight limit with a 30" barrel.

                    While I'm certainly hitting the point of diminishing returns at 30", it is still worth it to get speed. The 90g .224 bullet needs it for sure to buck the wind as well as a 202g .308. bullet. I'm making an F-Open 6mm Dasher with my custom case and chamber improvements that I am expecting to do well using a 30" 1.25" barrel and I'm making a 32" or a 34" (if it makes weight) version for my friend so we can see who beats who.

                    I recently made a pair of 30" Palma contour .223 rifles for two of my friends for competition. They won first and second place in our NRA Regional F-TR class 600 yard competition a couple weeks ago with them. I choose barrel length by running a Quick Load analysis for a cartridge to determine the boost I can achieve with incremental barrel length. The longer you get, the more barrel whip and torque you get so I have to use larger diameter barrels to eliminate that. It works! The no-taper 1.25" barrels don't flex or torque much at all.

                    I made a 600-1000 yard F-Class Open rifle for another friend a month ago in 6.5x.284. The hottest load in the Hornady manual is 2600 fps for a 160g bullet using this cartridge in a 24" barrel. This rifle shot the 156g Berger at 3200 fps (yes, that is 600 fps faster) with acceptable pressure in a 30" barrel. I recommended that he shoot it at 3000 fps or less to save barrel life but it would be OK to move up to the 3200 fps accuracy node if he gets to the Nationals to beat the .300 WSMs and 7mm WSMs at 1000 yards if it is windy. Because the real heavy barrels don't flex or torque, that rifle shot 15 consecutive shots with each having an incremental 0.2g powder increase through the same hole at 100 yards. Velocities ran from about 2700 fps to 3200 fps in that string. The hole got about 1/8" higher than bullet diameter from the first shot to the last shot because of the velocity increase.
                    Last edited by DakotaMan; 11-29-2020, 09:40 PM.

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                    • #11
                      Article by Dave Emary about stability of powder. One table shows the life span of 'deterrent' coating was interesting. At 70deg it will last 1700 years. At 140 deg it lasts 2.2 years. So storage conditions are critical. Deterrent controls how consistent the speed powder burns. Some new powders that are more stable are Hodgeon's Extreme powders, Reloader 16,23,25,33. IMR 4166,4451,4955,7977.Ball powders are more variable with temp. Some cartridges can be dangerous in hot temps with such powder as W760 in 22-250, .220swift or .243 Older ball powders can vary 150 to 200 fps changes on either side of ambient. Cold temps have little effect on powders. Smell powder and if 'sweet' smelling and no brown cloud it is probably o.k. If acid smelling and brown dust coming out, dispose of it.
                      Article in G&A January 2021.

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                      • #12
                        I don't subscribe to Guns & Ammo. But, Dave Emary has a blog and here's a 2016 article on powder temperature stability.

                        Powder Temp Stability: Hodgdon Extreme vs. IMR Enduron - PrecisionRifleBlog.com


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                        • #13
                          I think he revised his table. My guess is he got the info from a powder manufacturer as he goes into how the powder flake is bent so the 'deterrent' can be applied in the crack. Very technical.

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                          • #14
                            Originally posted by jhjimbo View Post
                            I think he revised his table. My guess is he got the info from a powder manufacturer as he goes into how the powder flake is bent so the 'deterrent' can be applied in the crack. Very technical.
                            Good info though. Thanks for sharing it.

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