Sizing 30 cal bullets for a .308 win.

As I have said in other sections of the forum, I am brand new to casting and am reading everything I can before actually getting started.

I will start off casting boolits for a .308 winchester to be used exclusively for hunting Whitetail in North Carolina. I have gotten lot of good info from all of you concerning what molds and alloys to start with, and I thank you for all of it.

In reading the "Lyman cast bullet handbook" and "Jacketed Performance with Cast Bullets", I have gathered that I am probably going to need to do some experimenting to determine what diameter boolit will work best in my particular rifle and what sizer die will work the best.

I am wondering what a good starting point would be? If the mold is supposed to cast to .309", should I start with the .309" die and just be ready to grind the mold if that ends up being too small? Should I try the .311" sizer and basically use unsized boolits in most cases? Should I bite the bullet and have a larger diameter mold made? What size boolits do ya'll use for your 30 cals? I have heard/read anything from .309"-.311".

If it were me the first thing I would do is cast a few up and take note on the size it comes out of the mould. Use a couple of those to find out what your barrel diameter is at the chamber and another one for your size at the muzzle.

All rifles are not created equal in this instance, your going to have to find out what yours like. My bore checks out at .308 and uses .309 boolits just fine. Yours may not that's where patience and notes help a fellow out.

I hope you have an accurate way of checking the diameter of you boolit when you pop it out of the barrel. And it would be a good idea to know what mould it is you plan on using.

You wanted to know what a good starting point was, find out what your bore size is and go from there.

There is no answer to your question other than, it depends on your rifle, but that is not what you want to hear.

Size .310 and see how that works. If you are happy, then you are done. If you are not happy, then go up and down .001.

It really depends on the dimensions of your bore and throat. Slug the bore, and the throat if you can; if you can't get the throat slugged, measure the inside of one of your fired cases to find out the maximum diameter that you can use (you need to have room for the brass to expand and release your boolit).

I size most of my ".30 cal" boolits to .311", but both of my .308's are milsurp.

Robert

Like Robert I size most of my 308 cal stuff at .311. I have one rifle I know likes .310 just as well, but I'm basically an entirely lazy person so I just leave the .311 die in and go. See what your mould drops in your alloy. Do NOT "grind" on the mould, whatever you meant by that. If you are so lucky as to have boolits drop at around .311, try them and see what the rifle says. Start with mid range loads in the 16-1700 fps area, see how the rifle reacts. Work up from there if the boolits seem to fly straight. Obviously if they don;t chamber you'll ahve to size down to .310 or lower. As a very general rule, fatter is usually better than skinnier in this game.

See what your mold will cast and slug your bore. Use both for a base line to go from.
If your bore is .308 and lets say the mold will cast .309 then try to lube the .309 bullet and not disturb it in diameter. See what happens. Generally, if your mold will drop the bullet the diameter that your rifle likes then do not alter the OD. The less sizing you do, the better off you are. I try to cast to the diameter I want then pan lube. Best not to alter the mold in any way unless it is the last resort.

You can alter your alloy to chage boolit diameter. Itisnt much butcould help

For my fairly recent M70 I size 0.3105...gotta slug the bore and do a pound slug to measure the throat.

SAAMI Min. .308 Win chamber will have .310 ball seat. Usual manufacturing tolerance is +0.0015"

If gun is NEW try .310

If gun has been shot some (over 500 rounds) try .311 and see how it runs.

If gun has been shot alot!!! So that throat is eroded, you may need to go .312"....