jump&crimp

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  • jump&crimp

    Hi guy's, Very new to the forum, just now starting to build a 6.5 with a Mega lowwer,a Liberty barrel from Satern and a Dillon upper,could I get some advice on the jump to start out with using Barnes TTSX ? Allso I have heard Pro's and Con's on crimping in the AR platform may I have some comments? Thank's fopr your reply Razor
  • rasp65
    Warrior
    • Mar 2011
    • 660

    #2
    razor
    You will most likely find that the 100 TTSX will need to be seated to mag length. However it is important to know exactly what length different bullets need to be seated at. This is my method:
    Take a properly sized case from the rifle you want to measure. Cut 2 slits into the neck down into the shoulder and clean up the burrs inside and out.
    Place the bullet you want to measure into the gauge.
    COAL Gage 1-1.jpg
    Remove BCG from rifle and insert gauge into the chamber. With a dowel push the gauge into the chamber until it stops.
    COAL Gage 1-2.jpg
    Use a dowel or a cleaning rod to push out the gauge from the muzzle. Some rifles you can tip the muzzle up and the gauge will fall out. However the Grendel has unique throat geometry that holds the bullet tight. It is important push the gauge out in order to get accurate readings. COAL Gage 1-3.jpg
    Measure the gauge and you will have the maximum COAL. Do this at least 3 times with different bullets from the same lot and average the length.
    COAL Gage 1-4.jpg
    As far as crimping there are no bullets that I am aware of that have a cannelure in the right place for the Grendel. I have found that my Redding dies have a lot of neck tension and have not had any problems.
    Attached Files
    Last edited by rasp65; 04-13-2011, 04:22 PM.

    Comment

    • bwaites
      Moderator
      • Mar 2011
      • 4445

      #3
      Originally posted by rasp65 View Post
      razor
      You will most likely find that the 100 TTSX will need to be seated to mag length. However it is important to know exactly what length different bullets need to be seated at. This is my method:
      Take a properly sized case from the rifle you want to measure. Cut 2 slits into the neck down into the shoulder and clean up the burrs inside and out.
      Place the bullet you want to measure into the gauge.
      [ATTACH]70[/ATTACH]
      Remove BCG from rifle and insert gauge into the chamber. With a dowel push the gauge into the chamber until it stops.
      [ATTACH]71[/ATTACH]
      Use a dowel or a cleaning rod to push out the gauge from the muzzle. Some rifles you can tip the muzzle up and the gauge will fall out. However the Grendel has unique throat geometry that holds the bullet tight. It is important push the gauge out in order to get accurate readings. [ATTACH]72[/ATTACH]
      Measure the gauge and you will have the maximum COAL. Do this at least 3 times with different bullets from the same lot and average the length.
      [ATTACH]73[/ATTACH]
      As far as crimping there are no bullets that I am aware of that have a cannelure in the right place for the Grendel. I have found that my Redding dies have a lot of neck tension and have not had any problems.
      Doesn't bumping it out with the dowel change the OAL?

      I can see that if they fall clear with tilting the rifle that it would work, but if you bump the nose of the bullet, how can you be sure you are setting it back?
      Last edited by bwaites; 04-17-2011, 07:47 PM.

      Comment


      • #4
        Doesn't bumping it out with the dowel change the OAL?

        My thoughts exactly. Why not use the BCG to pull the cartridge out and just catch it when it comes out?

        Comment

        • bwaites
          Moderator
          • Mar 2011
          • 4445

          #5
          Originally posted by WillD View Post
          Doesn't bumping it out with the dowel change the OAL?

          My thoughts exactly. Why not use the BCG to pull the cartridge out and just catch it when it comes out?
          I suspect that the bullet would still be caught by the grooves and would pull out.

          This is why Hornadys gauge is so effective.

          Comment

          • rasp65
            Warrior
            • Mar 2011
            • 660

            #6
            The outside diameter of the gauges neck with a bullet is less than the chambers inside measurement. It only takes a very light push to free the bullet from the throat. My gauge has a very tight grip on the bullet so I don't worry about pushing the bullet into it. I also repeat the process enough times to ensure the measurements are accurate. I had originally tried using the bolt to extract the gauge but found the measurements not to be repeatable. This gauge cost me $0.30.
            Last edited by rasp65; 04-13-2011, 10:24 PM. Reason: more info

            Comment


            • #7
              I can vouch for rasp's technique. I dremeled a case and gave the procedure a try, and with care, the process is quite repeatable to the thousandth. The case grips the bullet tightly enough that when you push out the bullet with a dowel or cleaning rod sans jag, there's no movement of the bullet in the case, allowing one to accurately measure cartridge OAL to reach the lands.

              Thanks, rasp!

              Comment

              • bronco_buster

                #8
                I do a variant of this with my bolt and autoloaders. I get a piece of allthread, 1/4x20, easily sourced at the big box stores. I sacrifice one case, I find Wolf Gold PPU cases to be useful for this...they already have the loose pockets after three firings...anyway I drill and tap the primer pocket 1/4x20, then I resize the case, then make my neck slots, then I screw the allthread into the base of the case. I run two nuts down the all thread to lock it so it won't turn in the chamber. Then I jam the lands with a dowel down the bore, that way I can feel exactly when the lands are contacted. A little back pressure from the dowel, and pulling the allthread and the measurements are very repeatable. After its out I just unscrew the all thread and measure length off the Ogive with a Sinclair bullet comparator. Very repeatable, easy, and the cases were recycling fodder anyway.

                Comment


                • #9
                  +1 to rasp65's method I have been able to get repeatable results with my Grendel and my .223

                  Comment

                  • PA_Allen
                    Warrior
                    • Mar 2011
                    • 333

                    #10
                    I use a variation on Rasp65's method. For magazine fed rounds for an AR-15, simply start off by seating the bullet in a resized case to 2.26" overall length. This is as close as you can get to the lands and still feed from the magazine. Push the cartridge into the chamber with your finger as far as it will go. (don't slam the bolt carrier closed or you may stick a bullet in the lands real tight!) Tip the rifle up. If the round sticks, the you are jammed in the lands. Tap the cartridge loose by using a cleaning rod or wooden dowel from the muzzel. Seat the bullet 0.005" deeper and repeat. It does not take many itterations to find a good starting point that will keep you out of the lands. With some bullets like the 100 and 120 Amax you may be suprised at how deep you have to seat the bullet to keep from sticking it in the lands.
                    Best,
                    PA

                    Comment

                    • Predmilitia
                      Bloodstained
                      • May 2015
                      • 61

                      #11
                      This is some awesome info. I appreciate when things like this are shared. Info may be a couple years old, but it's as golden to me as the day it was written.

                      Thanks

                      Predmilitia

                      Comment

                      • lwminton
                        Warrior
                        • Nov 2014
                        • 143

                        #12
                        RASP: How do you KNOW that the OAL hasn't changed? There is no way I can think of. The Hornady gauge is less expensive than wasting time with a measurement mistake.

                        Comment

                        • motoxxx_ryder
                          Warrior
                          • Mar 2015
                          • 180

                          #13
                          I dont use the dowel, the case usually has enough tension to hold the bullet if not run it through your die and it will give it enough.

                          Ive done this on all my rifles and can get a repeat measurement to the thousandth (.001) on them all. The biggest thing to remember on them is either remove the ejector or as you bring the case back push it against the wall opposite the ejection port cover. this will stop it from dragging on the wall and stop it from flinging out and possibly hitting the ground nose down.

                          Comment

                          • lrgrendel
                            Warrior
                            • Jul 2013
                            • 662

                            #14
                            Hornady Lock-n-load case length gauge......

                            Easy to use. Must buy a modified case and comparator to go with it though.

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