DIY monolitic bullet .323

Discussion in 'ELR, Ballistics & Bullets Board' started by sharp.shooter.ser, Jan 29, 2018.

  1. sharp.shooter.ser

    sharp.shooter.ser

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    I have ability and time to cut my own monolitic bullets for my 8x57. I ve scalled down a known monolitic 338 design, and cut it on my small cnc lathe. Now, I ve used brass (designated Ms58 half hard here, I dont have full specs). I am worried is it OK to use it as a material for it, or should I use copper instead? Or some other type of brass, if I can find any. And from what I have read, in load development I should use similar charges for those kind of bullets-weight (and start up low and work my way up) and consider QL as a help tool.
     

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  2. swd

    swd Yep that's me Gold $$ Contributor

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    I can't help with your questions, but they look great!
     
  3. sharp.shooter.ser

    sharp.shooter.ser

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    Thanks. I have available a CuZn39Pb3 brass, and I can get some CuZn36Pb3 brass too, and which one would be better for the application :D
     
  4. 6ShotsOr5?

    6ShotsOr5? Gold $$ Contributor

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  5. steve_podleski

    steve_podleski

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    what is the purpose of the grooves cut on the bearing surface?
     
  6. boltfluter

    boltfluter

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    I would assume to reduce bearing surface and pressure. :D:eek:

    Paul
     
  7. sharp.shooter.ser

    sharp.shooter.ser

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    From what I know they are refered as “drive bands” and yes they are to reduce pressure and bearing surface
     
  8. steve_podleski

    steve_podleski

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    Is pressure any higher than a lead core bullet?

    I think these drive bands would increase drag.
     
  9. sharp.shooter.ser

    sharp.shooter.ser

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    From what I have researched, yes and yes - it can generate more pressure than the standard lead core bullets - and thats why there are those drive bands, and yes they can and probably will increase drag.
     
  10. 6ShotsOr5?

    6ShotsOr5? Gold $$ Contributor

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    I think they could work like rings on a piston, sealing the gas behind them, but the reduced bearing surface area probably reduces the friction.
     
  11. USMCDOC

    USMCDOC Silver $$ Contributor

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    This is a 50 Cal Barnes Bore Rider.. might want to consider maybe something like this..
    BarnesBoreRider.jpg
     
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  12. sharp.shooter.ser

    sharp.shooter.ser

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    Ah, this looks nice, but I dont have the ability (at the moment) to cut the chamber in a way needed for these bore riders (to copy what 50 cal shooters do) nor do I have access to this type of bullet so I can take measurements down. I did write to several companies that produce these bullets, asking for help - to check on design-dimensions in regards to pressures involved. I sure hope to hear back from them too.
     
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  13. USMCDOC

    USMCDOC Silver $$ Contributor

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    Totally understand.. but what you really need are some numbers.. (for now that is).. but my thought was that instead of the "unequal" dia of the driving bands.. if they were instead both the same with the scalloped body like the bore rider?
     
  14. Canadian bushman

    Canadian bushman Silver $$ Contributor

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    The major determining factor for brass or copper is the use of the projectile. Brass for penetration, copper for expansion.( Im skipping over quite a bit here. )

    The ultra high b.c. bullets will usually be made from copper because it is more dense than brass.

    Neither brass or copper is as malleable as lead and therefore requires cannelures or “drivebands” to reduce bore pressure so you can reach the same or higher speeds, optimally, as lead and avoid excessive fouling.
     
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  15. JRS

    JRS Gold $$ Contributor

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  16. wi50shooter

    wi50shooter

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    360 brass bar stock is what you want to use. When you run your tool path offset have everything adjust on the same line, then mic on the final driving band and compensate over time from there. Measuring off the last driving band makes it easy if the tool offset follows through to the single change for one offset. When you sort bullets sort them to the 0.0001" on the last driving band into lots and then proceed to weight sort the lots. You will have some good shooters then. Nice design. Try Messing around with ogive lengths and making a hybrid tangent/secant ogive. Keep it tangent through the bore/groove engraving diameter then go secant after that to increase b.c. That will make things easier when dealing with jump/jam and getting things to work easy. Those secant barnes 50bmg bullets don't fly worth a crap.. in any rifle. Your grooved bullet is on a good track. Are the driving bands front of the boat tail different diameters? Boat tail Should be 0.8 x bullet diameter for length and keep the angle 8-10 degrees. Don't round the rear corner of the boat tail either, part it off square.
     
  17. sharp.shooter.ser

    sharp.shooter.ser

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    Thank you for the ideas, I ll sure mic them during process. I was advised not to use brass if I want my barrel to live longer, and to concentrate on copper. On my make, all bands are same OD, and I didnt know that I should cut off straight at boat tail, will do that :)
     
  18. Canadian bushman

    Canadian bushman Silver $$ Contributor

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    I personally dont feel brass is any harder on a barrel than copper. In my experience it actually runs a little cleaner than copper.

    Brass, depending on alloy, is uaually a little harder and will have a slightly different design than copper bullets. Usually a little less surface area at the groove diameter.

    IMHO, copper is a better choice. It is denser and seems to have less bore pressure with very gradual transitions between bore and groove diameters. Like the photo JRS posted, which is conductive to lower form factors. Its just a bit more difficult to machine to super tight tolerances while maintaining nice surface finishes. I.E. <32 ra.

    Some guys have obviosly figured it out.

    Like wi50shooter stated, sorting monos is critical to accuracy.
     

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