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Thread: Bullet diameter larger than muzzle?

  1. #1
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    Bullet diameter larger than muzzle?

    Dumb question:

    How tight is an unfired bullet to the barrel in a revolver? Is the bullet deformed when propelled or is a bullet supposed to ,for example, drop through a barrel with no resistance?

    Thanks.

  2. #2
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    If a bullet was falling through the barrel, I would be worried.
    A bullet is supposed to be a little bigger than the barrel (but only by a few thousandths of an inch), or the rifling would have no effect on the bullet.
    "Lenin at least had an excuse for his mindlessness: he died of syphillis." - Standing Wolf
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  3. #3
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    Thats exactly what I have. Four thousandths. I understand as I read more.
    Thanks.

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    as for the force required part of your question...

    A jacketed bullet will require quite a bit of force to pass through the barrel. In fact, a wood dowel and a hammer might be needed.

    Unjacketed, or in other words, lead bullets, will pass through the barrel much easier. One reason why lead bullets typically require less powder in the casing than would a jacketed bullet. (These are general statements. There are exceptions everywhere of course.)

    You'll figure this stuff out if you ever have a squib round. Make extremely sure you safely inspect the barrel, and don't fire another round without being sure, if it ever happens to you!

    Otherwise, pick up a fired bullet some time, if you can find one intact. You will visually be able to see where it deformed in the rifling.

  5. #5
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    If you ever have to drive a jacketed bullet out (or any other for that matter) I would not use wood...

    Use a brass rod, it is the best, you can get one at the welding supply shops.

    Read many a thread, that talked about the calamity of wood, and problems

    Regards

  6. #6
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    I don't know that wood is all that bad. I've dealt with a couple stuck bullets and never had a problem (not to say there isn't potential...?). For me the softest material rod, that works, is what I'd prefer. A good hardwood dowel has been fine, and won't damage the bore. These have been lead bullets.

    A jacketed bullet probably requires brass rods or similar, simply because of the force needed to move the jacketed bullet. It takes quite a bit with say, a 16 oz. hammer, to move a jacketed bullet.

    I've read a few threads and articles myself. One detailed a story about powder residue still on the base of the bullet. A metal rod was used to drive the bullet out, made a spark, and launched the bullet out the muzzle, and the rod back toward the "driver." This sounds pretty plausible with a squib load.

    I'd be happy with brass too, but wood is softer and even less likely to damage anything. As long as the rod is the largest diameter possible, it shouldn't expand enough to become stuck as well as the bullet.

    I'll admit, if somebody pounds a wood dowel down on the point of a rifle bullet, you might have wedging issues... otherwise whats the concern?

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    I think it would be unlikely, without the case sealed pressure can't build to force the bullet to move. The brass case contracts after pressure drops, even if it didn't if they could most people would remove the case before trying to pound the bullet out.

    I've learned not to say that things are impossible though .
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  8. #8
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    beats me. I prefer to dislodge the stuck bullet from the breech/chamber end, forcing toward the muzzle. So for me the barrel is out of the pistol completely and I push toward the muzzle. Lead bullets don't even need a hammer sometimes.

    However, in a revolver you don't always have that option. Hopefully the case is removed, or the cylinder swung out if you force back toward the cylinder.

    Definitely a time to pay attention to the details when doing things like this.

  9. #9
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    A Different Perspective

    Rifled barrels have two diameters, groove-to-groove and land-to-land. With the optimal modern-type cast-lead bullet, the largest diameter (driving bands) would be identical with the groove-to-groove diameter and the diameter of the lubrication grooves would be identical to the land-to-land diameter. This is what someone who casts his own bullets and is seeking maximum accuracy might require and could order a custom mold to attain. Variations by one- or two-thousandths of an inch would not likely cause problems.

    Note that rifling designed for lead bullets will typically have deeper groves than rifling designed for harder, jacketed bullets, which typically don't carry lubrication in grooves.

    Soft-lead bullets tend to "obturate," which means that the base deforms to seal the expanding gas inside the barrel. In older cartirdges, including many obsolete offerings for older Colt revolvers, bullets had hollow bases to enhance this process. This was particularly the case for cartridges that used "heeled" bullets, as we see in .22 rimfires such as the .22 LR.

    With jacketed or hard-lead bullets, there is not much likelihood of obturation, therefore excessive undersize will permit gas leakage around the bullet. Conversely, oversize by more than one- or two-thousandths of an inch may start raising chamber pressures excessively.

    It is worth mentioning that some modern pistols, such as Glocks, HK's and most models of Kahr, use polygonally rifled barrels, as opposed to having grooves cut in them. In such barrels the use of cast bullets is discouraged for concerns that there will be undetected leading in the "corners," which could significantly raise chamber pressures.

    This is a short summary but I hope it helps.

  10. #10
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    It does.
    Thank you
    W

  11. #11
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    Thats exactly what I have. Four thousandths. I understand as I read more.
    More like nine or ten thousandths.

    In the US, most firearms have grooves .004" deep. Which means the groove diameter is .008" larger than bore diameter. Revolvers generally shoot best if they get smaller as they go forward -- a bullet .001 larger than the cylinder throat, a cylinder throat .001 larger than groove diameter.

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