Which Diameter To Size?

A while back I bought a Lee C312-185-1R (advertised as for the 303 Brit) mold to use for my 303s and a 30-40, and I cast a batch but haven't sized them yet. Yesterday I miked them and they are sure enough .312" (they weigh ~180 gr, I cast them fairly hard), and that raises questions in my mind: since 303s are almost =/> than .313", what's the deal? They are GC design, so is that supposed to keep leading down and make everything o.k.? I haven't cast a whole lot lately, and my interest was just getting back up to the "doing" point, but now I'm aggravated. And should I size them to .310 or .311 for the Krag, or just run them through a .312 sizer to lube them & seat the GC and see what happens? I think I'm answering my own question, but I would really appreciate your input...
Thanks,
George J.

Maj, USAF (ret)
Member, SCV
Life Member VFW, DAV, TSRA and MOAA
Benefactor Member, NRA

"A good plan, violently executed today, is better than a perfect plan executed next week."
- Gen George S. Patton

The Krag rifle has a long and quite large throat. Shoot those bullets as fat as you can. I have three Krags and shoot .314 bullet in them all, regardless of barrel groove diameter. Seat the bullet just deep enough to feed through the magazine.

Use gas checks and a good quality lube. 16 grains of 2400 will make you very happy. The diameter of the cast bullet will vary with the alloy used, so .312 may not be the final word with that mold.

Last edited by Char-Gar; 05-03-2013 at 03:46 PM.

Disclaimer: The above is not holy writ. It is just my opinion based on my experience and knowledge. Your mileage may vary.

Boolit Mold Join DateFeb 2011LocationSouth East OhioPosts2

I came over here today to find the answer to the exact same question. I bought the same mold last month and am just now getting ready to use it.

It's relatively easy to open a Lee mould a thousandth using an abrasive (I use fine valve grinding compound) and drill the center for a screw to spin the boolit with a drill run slow. I cut the head off the screw and don't drill very deep to keep the screw from driving through and marring the mould, learned the hard way. I have opened some two thou. but if you go much further they tend to get out of round. Opening a size die is also easily done using a split dowel and emery cloth.

Rule of thumb with rifles is .002 or .003 larger than groove diam of
the barrel. Either try what you have or slug the bbl and set your diam
by the rule of thumb.

Look up "beagling" - a way to increase the casting diam of boolits by
simple, reversible addition to the molds (aluminum tape between the
faces)

Bill

If it was easy, anybody could do it.

can't believe we got all the way to post #6 to say this.
you got a couple of choices.
try em and see.
or measure the gun.
303's run from 308 through 318

it's all an educated guess,,,, till the trigger is pulled.

the more i find out about shootin boolits, the more it contradicts everything i ever learned about shooting jaxketed.

I'll just run them through my 312 sizer, lube & seat the GC & see how it goes. Long time ago when I started all this, I bought a .357 sizer for 38s, and it always worked fine. When I realized what I'd done, I bought a .358, and it worked fine...

Maj, USAF (ret)
Member, SCV
Life Member VFW, DAV, TSRA and MOAA
Benefactor Member, NRA

"A good plan, violently executed today, is better than a perfect plan executed next week."
- Gen George S. Patton

Trying different sizes/dia boolits to find the most accurate is to me, about half the fun of reloading (most of the time-with most boolits). Same holds true to me of trying different lubes.
1Shirt!

"Common Sense Is An Uncommon Virtue" Ben Franklin

"Ve got too soon old and too late smart" Pa.Dutch Saying

Maj, USAF (ret)
Member, SCV
Life Member VFW, DAV, TSRA and MOAA
Benefactor Member, NRA

"A good plan, violently executed today, is better than a perfect plan executed next week."
- Gen George S. Patton

you can't size them up. [you can swage them bigger though]
you can seat the gas check and lube them in a larger sizer.
we are playing with .001's here.
and sometimes that much neck tension, or boolit diameter, is all it takes to bring things back around.

it's all an educated guess,,,, till the trigger is pulled.

the more i find out about shootin boolits, the more it contradicts everything i ever learned about shooting jaxketed.

"Half of bein' smart is knowin' what ya' don't know."
Robert P. Mizell

FLOYD FILES

Boolit Master Join DateOct 2010LocationVT, that Green Mountain StatePosts574

I'm gonna guess they'll be fine as cast for the .303, apply the GC with a .314" sizer die and shoot 'em. That's what I do with my Nagants. Can't speak for the Krag. Been having a little trouble finding GCs for that bullet. Have to hammer on Hornady .30 cals before sizing. Big shank, measures over .290"

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Abbreviations used in Reloading
Pointed Soft Point "Core Lokt"

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