grove diameter

[Alberta Separatist]

I noticed in the latest Lyman Cast Bullet Handbook regarding the grove diameter of .308; the author recommends .308 be sized to .308.
however the same mould used in .30 - 06 ; the author recommends .309 grove diameter.
I intend to cast for the .308 and want to use a Lee sizing and lube die; any recommendation for a particular grove diameter?

[Scharfschuetze]

For true .308 calibre barrels, I've used both .309" and .310" sized boolits with very good results. Others will chime in and recommend even larger boolits diameters.

You probably won't go wrong if you go with a .310" sizing die.

[JonB_in_Glencoe]

I size my boolits to .311 for my Win mod 70 in 30-06.

But, I will say that you should listen to your Gun, rather than Lyman (or me).

[JSnover]

The author recommends. He doesn't know your rifle the way you do. For a nominal .308, start with .309 unless you slugged you bore and you know it needs larger boolits.

[Boolseye]

Yup, .309" min. Lee doesn't even make a stock sizer in .308"

[runfiverun]

well he recommended 308 cause that was as big as the lyman mold he had would make his boolits.
once he got a replacement mold it was opened up all the way to 309, he had to do something to get the data shot and published so he went with it.
okay I'm kidding ...kinda.
if you can shoot a bore/groove diameter boolit and hold it in alignment with the centerline of the barrel.
that's what you want to do.
I don't shoot grossly oversized boolits in anything and 310 is about maximum in the 30 calibers for me. [and is pretty much my standard]
in other rifles.
I shoot 358 in my 358 win.
225 in my 223.
324 in my 8mm.
285 in my 7's
459 in my 45-70's
I do so because I don't want damage to the boolit.
the hard part is finding or making brass that holds things straight in alignment with the centerline of the barrel.

[Maven]

run5run's .324" (8 x 57mm Mau.) and .459" (.45-70) work very well for me as well. However, for my .30-06, .311" works best. As I don't own a .30Win., I can't advise, except to suggest the "sweet spot" will be between .309" - .311".

[Mal Paso]

The latest Lyman Cast Bullet Handbook messed up 44Mag too. It makes the Load Tables unusable for most of us who size a thousandth or two over groove.

[runfiverun]

it doesn't mess it up all that bad you only gain about 300 psi for every .001 over sized you use for your barrel.
until you get to about .004 then it goes up exponentially from there.
even oversized jacketed bullets can be used without any drama up to about the same point.