Case water capacity of different manufacturer of orig. Grendel and fireformed brass

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts
  • A1Vixen
    Bloodstained
    • Sep 2017
    • 40

    Case water capacity of different manufacturer of orig. Grendel and fireformed brass

    I want to collect a list of all the case water capacity and maybe of older brass and new Lapua?
    Or is there maybe a difference in Lapua 6.5 Grendel Brass in Europe and the US?

    What's my actual problem, the fireformed brass have lot less case water capacity then QuickLoad calculates and you can't use the loads in the reloading manuals.
    Ok that's no real surprise, that's why I bought new 6.5 Grendel Lapua brass and fireformed my old 220 Russian I used in my 6PPC before.
    Both have almost the same water capacity, but lot less then Quickload calculates and I still can't use the loads written in the reloading manuals, not enough case capacity.

    Now the surprising thing is that new S&B 7.62x39 brass fireformed to Grendel only have 0.7 grain less water capacity then my fired Lapua 6.5 Grendel.
    And they have more capacity than the original Hornady 6.5 Grendel brass!

    So here my avg. water capacity results after firing I would like to share and hope you could share your results to compare:


    6.5 Grendel factory brass:

    - Lapua 6.5 Grendel: 36.35 grain H2O / 1.524"
    - Hornady 6.5 Grendel: 35 grain H2O / 1.515"


    Fireformed brass:

    - Lapua 7.62x39: 33.73 grain H2O / 1.501" (Easy to form, poor capacity and they are extremely soft. You will have very fast overpressure signs -> 27g Tac with 128g Scenar!)
    - S&B 7.62x39: 35.58 grain H2O / 1.502" (They are quite tricky to form, doesn't work with a standard FL Die!)
    - used .220 Russian brass, served before in my 6PPC: 35.42 grain H2O / 1.487"
  • Whit
    Bloodstained
    • Jun 2018
    • 36

    #2
    Don't take this as gospel, because I'm not a QuickLOAD expert by any stretch, but I feel like QuickLOAD is just kind of buggy on grendel, period. I only use it to get me in the general vicinity of the ballpark for other cartridges anyway, and pretty much ignore most of the data it gives for grendel. The only thing I use it for is to compare powders' relative burn rates, etc. Its default H2O capacity for a case trimmed to 1.515" is 37.50 gr. I thought that sounded high as well, so I measured the capacity of fired, unsized brass (which is the capacity you're supposed to plug in for centerfire cartridges above .22 cal, I think). I measured about ten cases and took an average. I wound up with 36.2 gr H2O as my capacity average. Those cases were from Hornady SST factory ammo that had been fired, reloaded, and fired again.

    Comment

    • Klem
      Chieftain
      • Aug 2013
      • 3507

      #3
      A1,

      The difference between new and fired Lapua cases is;
      New/full-length-sized 35.13 gns H20
      Fired/full-length sized 35.92 gns H20

      I loaded old primers into 10 cases of each and measured using RCBS electronic scales.
      The fired cases have been re-loaded at least five times.
      No doubt there are slight differences due to case lengths and I didn't bother calculating the meniscus.
      Data here;


      Whit,
      I use Quickoad all the time and find it invaluable, including this calibre. I have calibrated the program to be more precise by saving the case measuring results in the active file. A grain of capacity makes a difference to peak pressure but given the program is so conservative it's not a safety issue. It does however give you more accurate predictions.

      Comment

      • Whit
        Bloodstained
        • Jun 2018
        • 36

        #4
        Whit,
        I use Quickoad all the time and find it invaluable, including this calibre. I have calibrated the program to be more precise by saving the case measuring results in the active file. A grain of capacity makes a difference to peak pressure but given the program is so conservative it's not a safety issue. It does however give you more accurate predictions.
        PM inbound

        Comment

        • A1Vixen
          Bloodstained
          • Sep 2017
          • 40

          #5
          Originally posted by Klem View Post
          The difference between new and fired Lapua cases is;
          New/full-length-sized 35.13 gns H20
          Fired/full-length sized 35.92 gns H20
          I'm wondering that you're measuring your case capacity after sizing?

          Normally I'm measuring mine after firing, before I resize them. And with my Creedmoor, 7,62x54R and other calibers this gives the best results.

          But the idea is not bad, trying to use the capability of resized brass for the Grendel.

          Originally posted by Klem View Post
          I use Quickoad all the time and find it invaluable, including this calibre. I have calibrated the program to be more precise by saving the case measuring results in the active file. A grain of capacity makes a difference to peak pressure but given the program is so conservative it's not a safety issue. It does however give you more accurate predictions.
          How did you calibrate QL for the Grendel, other than changing the water capacity?



          I hope my case problem is history now. Yesterday I wanted to buy 200 new 7,62x39 S&B to fireform them but then I noticed that they finally got Lapua Grendel brass.
          I bought 300 for my AA AR15.

          So f*** on the reloading books and QL for this caliber. I will load ladders with 2-3 shots and going up each time about 0.2 grain. So I will inspect my brass after each group and find my own max. for my rifle with pressure signs.

          @Whit
          Your measured 1.2g more for the SST factory brass. That's a lot of difference.

          My Lapua Grendel brass results based on the cases from my bolt action rifle. (payed almost 200€/100pcs for them! Happy that I can get them now for a reasonable price here in Europe.)
          I am curious what I will get as results in the AR15 after firing.
          Last edited by A1Vixen; 07-28-2018, 06:30 AM.

          Comment

          • Klem
            Chieftain
            • Aug 2013
            • 3507

            #6
            Originally posted by A1Vixen View Post
            I'm wondering that you're measuring your case capacity after sizing?

            Normally I'm measuring mine after firing, before I resize them. And with my Creedmoor, 7,62x54R and other calibers this gives the best results..
            The reason for measuring water capacity after sizing is because this is the capacity that will be filled with powder. While it's more convenient to fill fired cases with water while it still has the used primer in it the fire-formed volume is larger than it will be. There won't be much difference between the two I admit so it depends on how real you want the measurements to be.


            Originally posted by A1Vixen View Post
            How did you calibrate QL for the Grendel, other than changing the water capacity? ..
            Obviously barrel length needs to change to suit. I change the cartridge length to coincide with my mags (58mm instead of the default 57.4mm). I leave the Weighting factor on 0.5 unless I want it to be more conservative, then I go 0.6, or less conservative, 0.4. QL is conservative anyway so there's no reason to go 0.6, especially in this calibre. I don't touch the Shot Start Pressure because it makes only cosmetic differences to the outcome. That's about it, unless it's a new bullet and then I choose a similar bullet and change the parameters like boat tail dimensions and Save. Just changing the cartridge OAL and case capacity will give you quite a different outcome. I ignore the predicted muzzle velocity as this can vary up to 100fps depending on what time of year it is. I focus on everything else, especially Peak Pressure.

            I don't imagine Lapua makes different brass for different parts of the world. Cadbury Chocolate does (different melting points), but not brass.

            Comment

            • Seitz333
              Unwashed
              • Jul 2018
              • 8

              #7
              FWIW - Using the same 5 pieces of Hornady once fired brass from my rifle:

              Fired Brass - Average 36.1gr H2O
              Sized Brass - Average 35.6gr H2O

              Chuck

              Comment

              • CastleBravo
                Unwashed
                • Oct 2017
                • 18

                #8
                Originally posted by Klem View Post
                The reason for measuring water capacity after sizing is because this is the capacity that will be filled with powder. While it's more convenient to fill fired cases with water while it still has the used primer in it the fire-formed volume is larger than it will be. There won't be much difference between the two I admit so it depends on how real you want the measurements to be.
                If you think about it, it's the case capacity during the firing process that truly matters, not case capacity before or after firing.

                I was told to use fired case capacity for rounds over 40ksi since the case obturates well before peak pressure.

                Comment

                • mdewitt71
                  Warrior
                  • Dec 2016
                  • 681

                  #9
                  I don't know about water capacity but, I do know the same exact hand load in Hornady, Lapua, and Starline brass give me 3 different Velocity Averages....
                  Starline being the slowest.
                  ― George Orwell

                  Comment

                  Working...
                  X