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Thread: Cast bullet hardness

  1. #1
    The Nostomaniac 03RN's Avatar
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    Cast bullet hardness

    Is 15 bhn to hard for .38 special loads? I just placed and order with rimrock and am wondering if 12 would be better.

  2. #2
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    Quote Originally Posted by 03RN View Post
    Is 15 bhn to hard for .38 special loads? I just placed and order with rimrock and am wondering if 12 would be better.
    15 bhn should be fine if the bullets are properly sized for the bore of your gun, ideally .001" larger than the bore.

  3. #3
    Site Supporter Trooper224's Avatar
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    It depends on the loading you intend to use. Unless you're going for light wadcutter type loads 15 should be fine. That should work for service level loads.
    We may lose and we may win, but we will never be here again.......

  4. #4
    The Nostomaniac 03RN's Avatar
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    Thanks

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    I load ACME 148 DEWC coated bullets that are a 16. I assume the 16 is pretty hard and would deform less than a standard softer hollow base wad cutter. Is my assumption correct?

  6. #6
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    I've used water quenched WW alloy (clip-on) for standard 38 spl loads, no problems at all,no leading of obturation problems, excellent accuracy despite an estimated 14-16 BHN. In my S&W 38s and 357s I sized them at .358", theoretically 0.001" above (again, estimated) bore size.

    IIRC, the lowest velocity I've tried was about 750 fps (chrono measured) out of a 4" barrel, with powders more or less equivalent to Unique or faster.

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    Fit to throats and bore is more important. Have you measured each? Pin gauges are cheap on Amazon and make measuring throats simple (Get .355, .356, .357, .358 to cover all possibilities). The barrel requires slugging.

    Chris

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    Quote Originally Posted by mtnbkr View Post
    Fit to throats and bore is more important. Have you measured each? Pin gauges are cheap on Amazon and make measuring throats simple (Get .355, .356, .357, .358 to cover all possibilities). The barrel requires slugging.

    Chris
    Can you explain more on this? What's considered a good fit between bullet and grooves and between bullet and throat?

    And does the degree of interference fit needed between the unfired bullet and the throat/grooves vary depending on the lead hardness and chamber pressure?

    I think the ultimate goal is to have good solid bullet obturation.

  9. #9
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    Quote Originally Posted by Alpha Sierra View Post
    Can you explain more on this? What's considered a good fit between bullet and grooves and between bullet and throat?

    And does the degree of interference fit needed between the unfired bullet and the throat/grooves vary depending on the lead hardness and chamber pressure?

    I think the ultimate goal is to have good solid bullet obturation.
    Sure! Working off memory here...

    The key to good accuracy is to have a bullet that is just slightly oversized for the bore and cylinder throats. Ideally your throats are the same or slightly larger than your barrel. If the barrel is larger, then you'd want to use a soft bullet in the hope that it would "bump up" or obturate under pressure to fill the barrel after existing the cylinder throat. Ideally you wouldn't want to rely solely on obturation through.

    Your bullets should be .001 over the largest measurement, which *should* be your throats. If you have particularly large throats and can't get bullets that fit, then a softer alloy, allowing for obturation, could help. I'm in this position with my S&W 25 because it has .457 throats and most bullets max out at .456 (those are mostly intended for BP revolvers).

    In terms of pressure, lead hardness can have an impact if the bullet is overly tight, but I've yet run into any noticeable issues strictly related to hardness. I have noticed pressure issues with too large bullets (such as .431 in my 629 with .427 throats). At the time, I was casting for a Redhawk (.432 throats) and the 629 (.427 throats) without sizing individually for each. Once I resized to the smaller spec, pressure signs went away and the gun got more accurate.

    Chris

  10. #10
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    Chris thanks for explaining. Learning more as I go.

    My reference to chamber pressure was in the context of how cartridges with higher pressures (magnums typically) can tolerate harder bullets without excessive leading since the higher pressure behind the bullet should help it obturate. Conversely, harder bullets (typically HBn 18 and above) lead like crazy in standard pressure loads due to improper obturation, which leads to gas escape between the bullet OD and the grooves, which leads to molten lead smearing all over the bore.

    At least that was my take from reading this: http://missouribullet.com/technical.php and this: http://www.lasc.us/FryxellCommentsCBAlloys.htm

    What's your take on all that?

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