Originally Posted by
Char-Gar
My non-scientific, non-chamber case, non-slug pounded way of determining which bullet size best fits the throat.
I am not a science type, nor much of a mechanical type of any kind. I tend to find my own way to do things with out regard to such things as casting, slugging and the like.
Over the years, I have accumulated 30 caliber sizing dies that run from .309 to .314 in .001 increments with a few in between the whole numbers. I take a large cast bullet and size it larger than I think I will need. I then load it in a dummy round and chamber it in my rifle. I take a look at the bullet with a strong light and a magnifying glass. If, it shows lead shaving of any amount. I size another bullet .001 small, load another dummy round and repeat. When I chamber a round that shows no lead shaving, but only a slight burnishing of the bullet surface, that is what I use. You could probably go .001 smaller and still do just fine.
This ain't science or engineering, but it works for me. An actual bullet in an actual case, chambered in an actual rifle IMHO is better than all the number in the world on a piece of paper.
I am sorry for the multiple posts on this subject. I don't want to sound like an arrogant jerk, but some of you guys showed an interest in learning about this stuff. I didn't learn any of this stuff on my own. I learned it from those who had traveled the road before me. I tested it out and found it to be true and it enabled me to get just about any rifle to perform well with cast bullets with a minimum of frustration, hair pulling and failure.
Bullet fit is the place cast bullet accuracy starts, but not where it ends. You must still consider;
1. Bullet style as it pertains to the internal profile of the barrel and it's rifling.
2. Bullet temper vis-a-vi, the pressure of the expanding gas.
3. The twist of the rifling vis-a-vi the length of the bullet and it's velocity.
4. Bullet lube that either works or doesn't work.
The above are not in order of importance, but if bullet fit is not correct, then all attention to other factors and details are a waste of time. Get the fit right and start from there.