Information on boolit diameter

[wallenba]

If I remember right, most here advise sizing a pre-patched boolit to bore diameter for smokeless. But I just read the following by Richard Corbin in his online book at his website.

" If blackpowder is to be used the unpatched bullet should be .003” to .004” smaller than the bore diameter. If smokeless is used the unpatched bullet diameter should be about .001” larger than bore diameter."

He really knows his stuff, but so do you guys here. So I'm wondering if it will make much difference or is it just a rifle to rifle thing? :???:

[docone31]

That sounds about right.
When I size my .308, I size the casting .308, then wrap. I then size the final wrap at .309.
It grows to .310. .001 sounds about right.

[wallenba]

That sounds about right.
When I size my .308, I size the casting .308, then wrap. I then size the final wrap at .309.
It grows to .310. .001 sounds about right.

What he is saying here is to size the UNPATCHED boolit .001 over bore diameter, then patch.

[303Guy]

Many say that yes but some say to size to fit the throat. Might have a lot to do with the rifles we are using. I'm not sure what influence alloy has on the equation. I think more in terms of aligning the boolit with the bore. I doubt the burning gases will cut through the patch even is there is a gas leak. I can't say - I've always patched as big will chamber (or at least, as big I could make them).

[Nobade]

I use paper that adds .006". For smokeless I want the finished bullet to be able to enter the mouth of a fired case, and fit into the throat. Hopefully both at the same time. This determines the bullet diameter before patching. For example, my 30-30. The throat is .310" so the bullet needs to be no bigger than .3095". This means the bullet starts out at .303" - .3035" and no bigger or smaller. The fired case will take a .311" bullet, so all is good there.

Black powder is another animal. Personally I don't use PP bullets in cartridge guns except loaded from the muzzle. But I do use them a lot in muzzle loaders. Again, the paper adds .006" and I want the finished product to be between .001 under bore size to no bigger than right at bore size. So my 45 caliber bullets need to be between .443 and .444 or they won't work. Too small isn't accurate, too big and they can't be loaded.

[pdawg_shooter]

Over the last 40 years of paper patching my experience has been best accuracy comes with sizing the bullet to .001/.0015 over BORE diameter. About the only paper I use any more is 16# green bar printer paper. Two wraps give me .010/.011 after drying, depending on how much stretch I give them. After drying, I lube and size to .001/.003 over GROOVE diameter. That is what works for me, and it works in every rifle I patch for. I have run into some that have a large throat and leaving the patch big enough to fill the throat helps a bit for accuracy.