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Please teach me about sizing cast bullets

1fisher1fisher Member Posts: 1,012 ✭✭
edited February 2010 in Perry Shooter Competition Shooting and Reloading Forum
I have done a fair bit of reloading, but am a total noob when it comes to cast bullets.

For a .300 Rook rifle, I am now casting a 85gr. bullet that comes out of the mold at .298". However, this bullet will fall right down the barrel of my rifle.

I have slugged the barrel, but I am having a hard time getting a good measurement as it is a very fine 7 groove rifling. I keep measuring it at .306" or .307".

So - what all do I need to "bump up" the bullet size from .298" to .307"??

I have read about lubrisizers, but do I really need that whole piece of equipment? I have just been lubricating the bullets in a pan and letting them dry on wax paper, so lube is not really an issue. Is there any kind of sizing die that would work in my reloading press?

Or should I just try to get a different mold that will put out a .307 or .308" bullet? (Not many around in the 85 - 90 grain sizes)

Thanks - any help will be appreciated!
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    richbugrichbug Member Posts: 3,650
    edited November -1
    To bump it up that much you would need swage dies. CH4D sells them for $120 or so.

    I would look for a suitable .308" mold myself. When it comes to lead bullets; being oversize is good, so long as it will readily chamber. 99% of the time an under size bullet will lead badly.
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    Tailgunner1954Tailgunner1954 Member Posts: 7,734 ✭✭
    edited November -1
    You want your sized bullets to be about .001 larger than your groove diameter.
    You may need to alter your alloy, esp if your mold is supposed to be dropping at .310.
    If your mold is supposed to be dropping them where it is, than you need to find a mold that drops that weight at a .310 diameter (and either use a alloy that drops them at .308 or push them through a .308 sizing die)

    Sizers make bullets smaller, not larger, and round. You need to first "bump up" your current bullets by compressing them lengthwise than running through the sizer.

    LEE does make a press mounted bullet sizing die.
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    jonkjonk Member Posts: 10,121
    edited November -1
    Get a new mold. A Lee 308 mold will set you back less than $20.

    The issue will be, the .300 rook calls for a true .300 diameter bullet. Sounds like you have an oversized bore (common). The question is, will a .308 chamber? you might need to make a chamber cast using cerrosafe to find out.
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    bpostbpost Member Posts: 32,664 ✭✭✭✭
    edited November -1
    The site below is the Mecca of cast bullets. Spend an hour or so there and get a great education.

    http://www.castboolits.gunloads.com/

    Normally cast bullets should be sized to be .001 larger than bore diameter, for you .308 should work fine. Cast bullets require lubrication before shooting. Lee has some tumble lube bullets that may suit your needs, I don't like or use tumble lube, but many folks do.
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    1fisher1fisher Member Posts: 1,012 ✭✭
    edited November -1
    It does look like a new mold will be the cheapest and easiest way to go. I'll just have to keep looking for one.

    Thanks for the help!
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    Tailgunner1954Tailgunner1954 Member Posts: 7,734 ✭✭
    edited November -1
    quote:Originally posted by jonk
    The issue will be, the .300 rook calls for a true .300 diameter bullet. Sounds like you have an oversized bore (common). The question is, will a .308 chamber? you might need to make a chamber cast using cerrosafe to find out.


    Back than, a lot of the cartridges used undersize bullets made of soft lead and depended on "obturation" to swell the bullet up to the required diameter.

    Your mentioning the chamber cast is a good point, as he wouldn't want to get into a pinch situation at the case mouth. Another alternative would be to find a local machine shop that has a set of "Gauge pins" and use those to determine what size the chamber is in the case mouth area.
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    elubsmeelubsme Member Posts: 1,996 ✭✭✭✭
    edited November -1
    Did you cast your bullets from very soft pure lead? If so they may expand enough when fired to engage the rifling. A lot of the old black powder cartridges worked on this principle. Don't try this if the bullets are cast from a mixture of tin & lead. I could experiment with the soft bullets, drilling a .306 diameter hole in steel stock, polishing the inside. (you could use a .308 sizing die, if you have one). I would then get a nose punch and bump the bullet up to .307 or so using a press, vise, or one good lick with a wooden mallet. One down side, if your bore is oversize and the chamber is not, the larger bullet will not chamber. This sounds like a fun project[:)] Ed
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    dtknowlesdtknowles Member Posts: 810 ✭✭✭✭
    edited November -1
    Do you have a fired case? What is the inside diameter of the mouth of that (unsized) fired case? That would be the largest diameter bullet that would be safe to use in you gun with those cases.

    +1 on going to cast boolits forum. They will tell you there how to lap your mold to increase the diameter but it would be easier to get a mold of a larger diameter and size your bullets down to fit your bore.

    I don't know how thick your brass is but you could neck turn to allow larger diameter bullets.

    Is your gun a Martini, would you consider breach seating the bullets?

    Tim
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