Bullet diameter vs. Bore diameter
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    Tinhorn
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    Bullet diameter vs. Bore diameter

    I've got a quick question. Seems most statements I've found here suggest .001 to .002" larger bullet than bore diameter, for cast bullets.
    However lots of people also recommend .460" diameter bullets. So am I to assume that most people's bores measure .458"?
    So if I have a smaller diameter bore,(grove diameter) then I should use a smaller bullet?

    It just seems to me that if I have a barrel that is sized to say .456" and I shoot .460" cast bullets, then the rifling would "scrape" off quite a bit of lead once the bullet is being forced into the barrel.

    I'm trying some cast bullets with different diameters to see what my gun likes in order to get as little leading as possible.
    I know each gun is different, and must be loaded as such, just wondering what the consensus was regarding this issue.

    Thanks!
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    "IF" your bore slugs at .456---------you should look at .458------------"IF" your bore slugs at .457------------you should look at .459------------> and so on.

    Steve
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    Deadeye
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    The size .460 is to help fill the throat On the Marlin Chamber which helps to center the bullet with the bore. But some find that .459 works just fine for them.

    But I will say that Ranch Dog did not come to the size of .460 simply by chance or Accident.

    If you go to Ranch Dog Outdoors . Com you can look at a chamber drawing of a Marlin which will help along with lots of other good information.

    Happy Trails.

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    DWB
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    The bore on my 1895CB (ballard rifling) slugged 0.456". I routinely shoot cast boolits (gas checked, heat treated to a BHN of 22, and bevel based boolits cast from Lyman #2 alloy and air cooled - BHN of ~15 or 16) sized to 0.459" and they shoot quite well. The bore on Marlin .45-70's typically isn't nearly as "generous" as the bores on Marlins chambered for .44 Mags or .444's.

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    Tinhorn
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    So what happens to the cast bullet that is .460" that is shot through a barrel dia. of .456"?
    Does the lead kind of "peel" back and hang on the back of the bullet? Or does the bullet possible "stretch" in length and narrow up to fit the bore?
    Seems that the hard rifling would shave off the excess lead of the fairly large oversized bullet.
    I'm not trying to argue or disagree with anyone, I'm just trying to understand what happens to the cast bullets when they are shot.
    I figure if we used measurements with quite a bit of difference, we might find some issues, kind of like using very small bullets in a larger diameter bore?

    Is there an area of "diminishing returns", regarding the "exact" fit of bullets or lack thereof?
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    Quote Originally Posted by Ratdz View Post
    So what happens to the cast bullet that is .460" that is shot through a barrel dia. of .456"?
    Does the lead kind of "peel" back and hang on the back of the bullet? Or does the bullet possible "stretch" in length and narrow up to fit the bore?
    Seems that the hard rifling would shave off the excess lead of the fairly large oversized bullet.
    I'm not trying to argue or disagree with anyone, I'm just trying to understand what happens to the cast bullets when they are shot.
    I figure if we used measurements with quite a bit of difference, we might find some issues, kind of like using very small bullets in a larger diameter bore?

    Is there an area of "diminishing returns", regarding the "exact" fit of bullets or lack thereof?
    I think that they squeeze down to fit the barrel rather than shaving. Perhaps .002 over is optimum but it is likely better to be .003 over rather than be too small allowing hot gases to surpass the bullet and melt the lead. At least that is my understanding of it.
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    Deadeye
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    Quote Originally Posted by eaglesnest View Post
    I think that they squeeze down to fit the barrel rather than shaving. Perhaps .002 over is optimum but it is likely better to be .003 over rather than be too small allowing hot gases to surpass the bullet and melt the lead. At least that is my understanding of it.
    Ding Ding Ding We have a WINNER

    The bullet will squeeze down just fine.

    As for diminishing returns I am not really sure as I have never made anything larger than maybe .0035 overbore. But try different diameters of bullets and the rifle will tell you what it likes if you do your part behind the butt.

    You can also check this. Take a Fired piece of brass and measure the mouth of the brass and then size the bullet to that size. Then re-size the brass. Doing that will give you enough room for case expansion when fired to release the bullet correctly. But again the bore diameter will determine if you can get away with that size of a bullet for correct fit. So checking both will help one make a better self informed decision.

    Is Reloading Hard No Not really. But it does take a bit of concentration and problem solving at times. And the longer that you do it the more questions you will have and the better ammo you will make for a patricular firearm. This is where things really start to get good.

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    Hey Ratdz

    The term “.001 to .002” over bore diameter” for cast bullets – is a bit of a misnomer.
    The correct term is - .001 to .002” over groove diameter… The groove dia is the largest measurement in the barrel, and usually close to that of the throat/leade dia.

    Like GreenMachine said – you’ll want a bullet that’s larger than the throat/leade. This is the area where the bullets base must first seal the hot gases. If it doesn’t seal, the hot gas will cut up the driving bands and deposit molten lead along the barrel.

    I also size my bullets like GM – If a bullet will fit into a fired case by hand (for the rifle I’m loading for) – it’s the right size… For that GBL a .460” Ranch Dog bullet works.

    Firing a cast bullet at 25,000 psi – the barrel works just like putting the bullet thru a sizing die… only a lot quicker.
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    Danny

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    Wrangler
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    I have often considered trying some cast but in the end always abandon the idea because I can't be bothered! One of the Australian cast manufacturers I emailed about upsized bullets as they cast .458 but will upon request cast bigger but they actually recomended sticking with .458. So if cast is better bigger (?) how does a jacketed pill function in regards to escaping gas, etc?

    Apologies if it seems like a silly question, just curious.

    Cheers,
    Waldo
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    Quote Originally Posted by Waldo View Post
    I have often considered trying some cast but in the end always abandon the idea because I can't be bothered! One of the Australian cast manufacturers I emailed about upsized bullets as they cast .458 but will upon request cast bigger but they actually recomended sticking with .458. So if cast is better bigger (?) how does a jacketed pill function in regards to escaping gas, etc?

    Apologies if it seems like a silly question, just curious.

    Cheers,
    Waldo
    It's not a silly question, I asked the same some years ago and was told by a tech. at Nosler Bullet Co. that jacketed bullets don't erode like lead bullets. A tiny bit of gas may escape past jacketed bullets but it causes no issues. Any gas escape at all will cut the relatively soft lead which will then stick to the barrel causing the barrel leading that we all love and cherish. The much harder copper jacket does not melt quickly enough to cause an issue.

    Shooting jacketed bullets and shooting cast bullets are two different trails to follow, very little of either applies to the other.

    Waldo and pubfin like this.


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