Toons

Hi,I here about "free-bore" in the barel,what is the idea behind it or knowing about it's length?
Thanks
safty is #1

propmahn

free bore is an length of the barrel that has no rifling in it. it is there so that you have more control over the over all length of your cartridge.
as for its length that depends solelly upon the manufacturer, and it varies a lot.

propmahn

Toons

Thanks,that really made it clear.
so, i assume it's not important unless i am going to do my own bulet reloding?

Solitary Man

It is indeed the portion of the bore just ahead of the chamber that has no rifling. The reason it has no rifling is so that the cartridge can be easily chambered. If it was not there then when you tried to chamber a round the bullet would make contact with the rifling making it difficult, if not impossible, to properly chamber the round. You might even push the bullet back into the case trying to force the round into the chamber. Also, having the bullet in firm contact with the rifling can cause dangerous pressure spikes when the round is fired.

Why is it important to know where the rifling begins? Well, most handloaders believe that optimum accuracy is obtained with the bullet very close to the lands, maybe .020" or .030" off. Having the bullet close to the rifling, however, is not always going to guarantee accuracy, but in my experience it usually does help. If you're going to shoot nothing but factory ammo, then knowing where the rifling starts really doesn't matter since factory ammo is generally loaded well short of it.