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How much does seating deform your bullets?

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  • #16
    I was initially suspect of the mold. I'll know for sure when I mic all remaining bullets this weekend, sized and unsized. I do remember that Lee mold being finicky at first, maybe these were some bullets that looked good when dropped, but weren't actually round. If that is the case, they are just going back in the pot with a little extra flux!


    • #17
      Ok, so the deformation definitely shows up in the lubing/sizing process.

      I measured the 40 cast bullets I had left, all were .299"-.300".

      I measure the 35 I had lubed/sized. 10 were .300", 10 were .304"-.305", 10 were .306"-.308" and 5 were .309"-.310".

      Also, I double checked the luber/sizer (it is a RCBS Lube-a-matic, not Lyman like I had posted earlier) and there is a .310 die in it with a top punch designed for a flat point bullet.

      My Alloy is straight clip-on wheel weights +5% tin by weight. I have no leading with this allow and have literally shot 1000s of rounds with this batch of ingots (rifle and .44 Mag pistol with the Keith SWC #429421). Do you really think this is an alloy issue or maybe do you think my luber/sizer isn't warm enough and just adding too much friction to the process? I thought about maybe warming it up a bit and see if that helps, but honestly the most force happens when the gas check first goes in...

      I have tons of Magnum shot, I could add that to the next pot and see what happens...


      • #18
        Half as much tin is plenty. You need a better nose punch too.
        I was raised in the 50\'s on jackrabbits and gunpowder.salt and pepper wooda made\'em taste better


        • #19
          Ever been to an "old school" chiropractor? Back when the tables were plywood and had the look of something out of a "B" rated horror movie?

          If so,then you experienced what a bullet gets put through on some GC seating/sizing ops. Best described by Vincent Price,with some spooky music in the background ( hey it's Halloween,haha)..... anyway, the bullet structure is getting put under tension when the GC is first introduced to the die.This force builds as it gets to where the die leade in changes to the straight section..... then humps or bumps as it conforms to the shape.

          Dosen't happen with every bullet die combination. But when it is pronounced, the nose takes a sudden shock. It's at this point the nose gets deformed, just like cracking your back on a chiro's table. It's supposed to be controlled, but it isn't. It takes a much longer nose die and usually a custom "H" die to have complete repeatability. And even then there's a technique to it. Get it right,along with a few other things admittedly.... but bumped noses on bore riders can really make a difference with accuracy. You also have this opportunity to reshape meplat. Good luck with your project.