Hot weather shooting caused overgassed symptoms...

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts
  • txgunner00
    Chieftain
    • Mar 2011
    • 2070

    Hot weather shooting caused overgassed symptoms...

    Just sharing some pics of some brass I had to cull. These were some of my loads that I knew were on the edge of hot but I never got any flattened primers, extractor marks or other signs of pressure. They were shot on a 110+ deg day in full sun. ALL of my equipment was cooking! The best I can deduce the heat caused the pressure to increase just enough to cause the bolt to start unlocking before the case had a chance to contract. These 5 cases were the worst. Another 10 or so had lines that were barely visible. All on the extractor side.

    case head pull.jpg

    To prevent this from happening I'll back the loads off a bit as much as I hate to. They were shooting exceptionally well, just like any other SMK I've loaded hot.
    NRA life, GOA life, SAF, and TSRA

    "I ask, Sir, what is the militia? It is the whole people, except for a few public officials. To disarm the people is the best and most effectual way to enslave them."

    George Mason, co-author, 2nd Amendment.
  • txgunner00
    Chieftain
    • Mar 2011
    • 2070

    #2
    Rifle / Load data.

    Barrel- 20" Satern
    AA brass
    CCI450
    IMR 8208- 28.6 gr
    123 smk
    2.265 COL
    Last edited by txgunner00; 10-30-2011, 03:28 AM.
    NRA life, GOA life, SAF, and TSRA

    "I ask, Sir, what is the militia? It is the whole people, except for a few public officials. To disarm the people is the best and most effectual way to enslave them."

    George Mason, co-author, 2nd Amendment.

    Comment


    • #3
      Originally posted by txgunner00 View Post
      Just sharing some pics of some brass I had to cull. These were some of my loads that I knew were on the edge of hot but I never got any flattened primers, extractor marks or other signs of pressure. They were shot on a 110+ deg day in full sun. ALL of my equipment was cooking! The best I can deduce the heat caused the pressure to increase just enough to cause the bolt to start unlocking before the case had a chance to contract. These 5 cases were the worst. Another 10 or so had lines that were barely visible. All on the extractor side.

      [ATTACH=CONFIG]530[/ATTACH]

      To prevent this from happening I'll back the loads off a bit as much as I hate to. They were shooting exceptionally well, just like any other SMK I've loaded hot.
      LOL and what makes ya think those was too hot....
      TX what was yer groups like?
      BTW looks realll close to head separation

      Comment

      • txgunner00
        Chieftain
        • Mar 2011
        • 2070

        #4
        gren 1000.jpg

        5.092" @ 1000

        Yep- only one out of 100 pieces came close to separating but that would be one too many.
        NRA life, GOA life, SAF, and TSRA

        "I ask, Sir, what is the militia? It is the whole people, except for a few public officials. To disarm the people is the best and most effectual way to enslave them."

        George Mason, co-author, 2nd Amendment.

        Comment


        • #5
          Brother yer lucky on those
          a small lunch box with a blue ice thingy would have worked wonders for ya on that

          Comment

          • bwaites
            Moderator
            • Mar 2011
            • 4445

            #6
            The infamous belted Grendel case!!

            That load was a tad warm in more ways than one!

            Comment

            • txgunner00
              Chieftain
              • Mar 2011
              • 2070

              #7
              It was 0.1 over book max but I had no other issues in 300+ firings prior to this. A cooler would have been a good idea that day.

              BTW does anyone make a ruptured cartridge extractor for 6.5 gren or similar?
              NRA life, GOA life, SAF, and TSRA

              "I ask, Sir, what is the militia? It is the whole people, except for a few public officials. To disarm the people is the best and most effectual way to enslave them."

              George Mason, co-author, 2nd Amendment.

              Comment


              • #8
                not that I am aware of but would a 6.5x55 with the rim turned down to .440" not work???

                Comment

                • RangerRick

                  #9
                  Originally posted by txgunner00 View Post
                  Rifle / Load data.

                  Barrel- 20" Satern
                  AA brass
                  CCI450
                  IMR 8202- 28.6 gr
                  123 smk
                  2.265 COL
                  First off, thanks for sharing this.

                  I thought 8208 was temp stable? If that's the case, it would indicate that the load was too hot, regardless of weather.

                  Could it be that those cases were just wearing out after multiple reloads?

                  The normal failure mode is split necks. You may want to measure the case head expansion after shooting new brass.

                  I don't think they failed because the extractor was yanking them out under pressure. They failed on the extractor side because that's the least supported part of the case and the over pressure allowed the case head to move the most there.

                  If they were yanked out under pressure the whole case would be abraded and very dirty. These look pretty clean and shiny without scratches.

                  Don't kid yourself that these are the only cases with a problem. Use a jewelers pick or even a paper clip straightened out with a small "L" on the end to feel inside your cases near the head.

                  Sharpen the short leg of the "L" so you can feel cracks or stress lines inside the case.

                  I'll bet you find some with cracks on the inside that don't show on the outside

                  RR
                  Last edited by Guest; 10-29-2011, 05:19 AM.

                  Comment

                  • Drifter
                    Chieftain
                    • Mar 2011
                    • 1662

                    #10
                    That charge weight of 8208 with 123gr bullets is excessively hot in any of my barrels and chambers. 8208 in the 6.5 G seems a little volatile to me, as it goes from safe to unsafe with relatively small changes in charge weights. And there seems to be mixed feelings elsewhere on the 'net regarding its temp sensitivity. I like AR-Comp powder much better in the Grendel.

                    That COL, while possibly appropriate for the 123gr Scenar, seems rather long for the 123gr SMK. Are you certain that the bullet isn't getting jammed into the lands (resulting in higher pressures)?
                    Drifter

                    Comment

                    • Drifter
                      Chieftain
                      • Mar 2011
                      • 1662

                      #11
                      Originally posted by txgunner00 View Post

                      BTW does anyone make a ruptured cartridge extractor for 6.5 gren or similar?
                      It's possible that a 7.62x39 BSE might work, such as this:

                      Cheaper Than Dirt! is America's Ultimate Shooting Sports Discounter, and we live up to that title. Expect bulk ammo deals, discount firearms, parts to build your next gun and more.
                      Drifter

                      Comment

                      • txgunner00
                        Chieftain
                        • Mar 2011
                        • 2070

                        #12
                        Originally posted by RangerRick View Post
                        First off, thanks for sharing this.


                        I thought 8208 was temp stable? If that's the case, it would indicate that the load was too hot, regardless of weather.

                        It was definitely on the edge but I got no other indication of pressure prior to this.

                        Could it be that those cases were just wearing out after multiple reloads?

                        shouldn't be. these only had 3 loadings

                        The normal failure mode is split necks. You may want to measure the case head expansion after shooting new brass.

                        I don't think they failed because the extractor was yanking them out under pressure. They failed on the extractor side because that's the least supported part of the case and the over pressure allowed the case head to move the most there.

                        If they were yanked out under pressure the whole case would be abraded and very dirty. These look pretty clean and shiny without scratches.

                        These were dirtier than usual after firing. They have been tumbled.

                        Don't kid yourself that these are the only cases with a problem. Use a jewelers pick or even a paper clip straightened out with a small "L" on the end to feel inside your cases near the head.

                        Sharpen the short leg of the "L" so you can feel cracks or stress lines inside the case.

                        I'll bet you find some with cracks on the inside that don't show on the outside

                        I have a dental pick I do this with. I only fired 20 or so on the 110 deg day. The rest of the lot of 100 loads I fired on hot days but from a covered bench and they are fine.


                        RR
                        xx
                        Last edited by txgunner00; 10-29-2011, 03:27 PM.
                        NRA life, GOA life, SAF, and TSRA

                        "I ask, Sir, what is the militia? It is the whole people, except for a few public officials. To disarm the people is the best and most effectual way to enslave them."

                        George Mason, co-author, 2nd Amendment.

                        Comment

                        • txgunner00
                          Chieftain
                          • Mar 2011
                          • 2070

                          #13
                          Originally posted by Drifter View Post
                          That charge weight of 8208 with 123gr bullets is excessively hot in any of my barrels and chambers. 8208 in the 6.5 G seems a little volatile to me, as it goes from safe to unsafe with relatively small changes in charge weights. And there seems to be mixed feelings elsewhere on the 'net regarding its temp sensitivity. I like AR-Comp powder much better in the Grendel.

                          I started developing this load early spring this year and chronoed them in temps from 40 deg to 100+ deg. The average velocity never deviated more than 10 FPS. Unfortunately I was not measuring them on the day I got these.

                          That COL, while possibly appropriate for the 123gr Scenar, seems rather long for the 123gr SMK. Are you certain that the bullet isn't getting jammed into the lands (resulting in higher pressures)?
                          That's the COL I came up with when I started developing these loads. Wouldn't hurt to check it again I suppose.
                          NRA life, GOA life, SAF, and TSRA

                          "I ask, Sir, what is the militia? It is the whole people, except for a few public officials. To disarm the people is the best and most effectual way to enslave them."

                          George Mason, co-author, 2nd Amendment.

                          Comment

                          • txgunner00
                            Chieftain
                            • Mar 2011
                            • 2070

                            #14
                            Originally posted by Drifter View Post
                            It's possible that a 7.62x39 BSE might work, such as this:

                            http://www.cheaperthandirt.com/SKS080-31.html
                            Might need a little adjustment but it should work.
                            NRA life, GOA life, SAF, and TSRA

                            "I ask, Sir, what is the militia? It is the whole people, except for a few public officials. To disarm the people is the best and most effectual way to enslave them."

                            George Mason, co-author, 2nd Amendment.

                            Comment


                            • #15
                              Originally posted by txgunner00 View Post
                              Might need a little adjustment but it should work.
                              30 cal head (neck) versus 6.5 would need machining at the neck mate up area for extraction use
                              it could work provided it was machined correctly

                              Comment

                              Working...
                              X