I have had a VZ-24 Mauser rebarreled with a Shilen barrel, in .300 Win Mag, by a good and experienced gunsmith. The gunsmith's work looks first-rate; but I haven't had a chance to shoot it yet. In preparing loads for it, I have determined that with a 180-grain bullet seated out so that it touches the lands, the cartridge OAL is 3.601". (I don't intend to actually load the cartridges so that they are into the lands; I just wanted to find out how far one would have to seat the bullet to touch the lands.) However, the magazine is only 3.345" long, internally. Therefore, in order for the cartridges to function through the magazine, the bullets will have to be seated over 1/4" off the lands. I assume that the amount of freebore will increase as the rifle is used and the throat erodes. Is this too much freebore? Is there a level at which the freebore becomes excessive and unsafe?

There is no level at which freebore becomes unsafe. Basically, all else being equal, more freebore reduces peak pressure.

You may be able to a few more grains of powder and achieve higher velocity with that freebore. This is the Weatherby approach to high velocity...

However, in general a long freebore is not usually associated with best accuracy so it may be excessive from this perspective.

Having said that, I will note that I've had some extremely accurate loads in many rifles with a LOT of freebore! The most accurate load I ever had for an old .270 Win was with a 90gr Sierra varmint bullet seated so deep that I almost didn't bother test firing for accuracy because conventional wisdom said it would not shoot well! This load had about the same freebore as you mention, but that load shot MOA for well over 2000 shots and accounted for a boxcar full of groundhogs.

In other rifles I have experimented with seating depth and often the best accuracy has been with the bullet very close to the rifling. However, sometimes best accuracy was with quite a jump to the lands (and this was regardless of how I played with compensating with powder charges in 2 particular rifles).

My conclusion? I dunno... sometimes I think each rifle is a law unto itself and you just have to try different seating depths and powder charges until you find what it likes!

Note that my comments apply to jacketed bullets: with cast, I've always found best accuracy with the bullet seated very close (or into) the lands.

I would not worry about the freebore unless you are unhappy with the accuracy!

YMMV,

jpb

[ 04-07-2003, 22:44: Message edited by: jpb ]

Winchester does it that way. It may be that factory ammo need the freebore to keep pressures down. The only one I ever loaded for shot fine. Weatherby does it that way too.

jpb and Scot: Thanks for the information; it is helpful.