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Cast Bullet collapsed in PC??

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  • Cast Bullet collapsed in PC??

    Anyone ever see this before? I've been PC'ing for a while now and all of a sudden I have projectiles collapsing during the baking process. These were some cast bullets I picked up cheap and the only thing I can think of is some sort of outgassing from the projectile. They were marked "Valient 115 grain RN .357" ". When purchased they were lubed. I double boiled, solvent cleaned then gave it a good shot of brake cleaner to clear and dry. None of the other projectiles in the batch show any markings from the screen mesh. Only the ones that collapsed. Thoughts?
    Attached Files

  • #2
    Soft alloy, how hot do you bake them?

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    • #3
      350F for 20 minutes. According to the standard BHN chart the bullets register about 18BHN on the chart. (.054" dimple after one minute of 60lbs pressure)

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      • #4
        Doesn't seem likely that they are melting with an oven 300* below the melting point of lead? Even if a corner were to have a hot spot.

        Have you weighed them? If they are supposed to be 115's and they are light maybe they have voids in them?
        Endeavor to persevere.

        Call sign: Limp Wrist

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        • #5
          I powder coat at 400* for 20 minutes. Melting temps, all Fahrenheit, for various alloys are below:
          Pure Lead 621*
          Monotype 512*
          Linotype 462*
          Clip on Wheel Weights 560*
          Tin (Sn) 450*
          Lead to tin ratio 50:50 405*
          Lead to tin ratio 10:1 563*
          Lead to tin ratio 20:1 590*
          Lead to tin ratio 30:1 600*
          Babbit metals 350-450*

          There are very few combos that will sink to the 400* melting temp of powder coat. Perhaps someone added an alloy to the pot that didn't get properly mixed or the thermostat on your oven is bad.

          Were any of these bullets directly over or under the heating element? Starting cold may expose the bullets right over or under an element to heat for a long time until the oven gets up to a temp that can be sensed by the thermostat. Kind of like the old adage of your feet in the oven and your head in the fridge. On the average you feel pretty good. But your feet will burn badly. RD
          Last edited by Rockydog; 04-02-2019, 20:44.
          Every once in a while in life we need a policeman, a lawyer, a doctor and a preacher. We need a farmer three times a day, every day.

          Et Canis Manducare Canis Mundi

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          • #6
            Did you make sure your oven was fully preheated. When preheating temps can spike way above thermostat temp. I melted a few this way

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            • #7
              Is it possible that there is a large void inside this bullet ?
              Salt&Light

              WOODSMAN777

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              • #8
                I guess my term of "outgassing" should have been "void". But that is my thought so far. some form of gas or void trapped inside and when heated it found its way out. But I still wouldn't have thought it weakened the walls enough to become soft or collapse. I'll weigh them when I get back to the shop. Just one if those "duh" moments why I haven't done that already.
                cylinderman I had the oven preheated toi 350 before I put the bullets in. I normally have the bullets upright but just testing a new powder so I just poured them out on the screen.

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                • #9
                  Just a wild guess, but I suspect some sort of contaminant in the alloy. it is either meting or volatizing, creating the voids. No idea what it could be, though, but obviously something that volatizes or melts way below the melting point of lead, tin, antimony, or other normal contents.
                  "The fact that guns can kill another human being is the whole point. That\'s why they are so darn good at deterring violent criminals". Ann Coulter

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                  • #10
                    Of the six bullets that collapsed 4 were 115.x. The low was 113.6 and high was 116.2. Just as good a spread as the Blue Bullets or Acme. I cut one in half horizontal across the collapse and no pocket is visible. Crushed one and no pockets but it seemed more brittle than I expected . It cracked when nearing flat rather than crush evenly. I'll cut one vertical tomorrow but I'm stumped.
                    I'm guessing from the reply's no one else has ever experienced this.

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                    • #11
                      Turn down the oven 50 degrees
                      I was raised in the 50\'s on jackrabbits and gunpowder.salt and pepper wooda made\'em taste better

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                      • #12
                        Put an oven thermometer in there and find out what the temp really is.
                        +/- 25* is what ovens are supposed to perform to to pass inspection, but I've measured some that were over 75* too hot. I typically test at 350*.
                        It's not that Democrats are so damned ignorant. Their problem is that everything they know is wrong.

                        Wimachtendienk, Wingolauchsik, Witahemui

                        He who knows not and knows not that he knows not, is a fool.
                        He who knows not and knows he knows not, is wise.

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                        • #13
                          Originally posted by olyeller View Post
                          Put an oven thermometer in there and find out what the temp really is.
                          +/- 25* is what ovens are supposed to perform to to pass inspection, but I've measured some that were over 75* too hot. I typically test at 350*.
                          This.

                          Ovens are NOTORIOUS for thermostats that are basically Delusional, also Hot Spots are common unless you actually have a Convection Oven (the air movement evens it out).

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                          • #14
                            Originally posted by Charley View Post
                            Just a wild guess, but I suspect some sort of contaminant in the alloy. it is either meting or volatizing, creating the voids. No idea what it could be, though, but obviously something that volatizes or melts way below the melting point of lead, tin, antimony, or other normal contents.
                            The oven is good guys. It's a convection that stays between 340 and 360 when set to 350. I cut another one in half vertically and still no sign of a cavity. Though I have to agree with Charley and Woodsman777 that either some contaminant or void was the cause. I was hoping someone else had seen this before and could educate me. ;-)
                            I'll chalk this one up to "dunknow" and leave those bullets for a future melting party.... Thanks for the help and suggestion. I always learn something form this group.

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                            • #15
                              Are you sure they are just a lead alloy? Some metals that appear to be lead have a lower melting point. I have used a lot of wheel weight alloy and some of my "mystery metal" (scrap, range and ??? lead) and I bake at 375-400 degrees for 20 minutes with no slumping/melting...
                              I\'ve learned to stand on my own two knees...

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