bullet diameter

[gjgalligan]

As somewhat of a newbie to reloading I have a question.
I was looking at .44 bullets some are .429, .430, and some are .431.

What difference does it make?

[testhop]

to you none BUT to your gun pleanty you need to slug your firearm to check what size it is
or try some of each size to see whitch groups best

[kg42]

Assuming we are talking cast/swaged, match the bullets to your chambers' mouths, or even add 1 thousand. Ideally the bullets will get squeezed again a little when reaching the barrel, but cylinders and bbl of same diameter are fine too.
Undersized lead bullets will leak gases+vaporized lead and lead the barrel.

With jacketed, match the bullet to the barrel; one thousand undersized might still be very accurate, but I don't like the idea of hot gases working the bore.

For both, oversized bullets will increase pressure so adjust your loads if you change diameters.

kg

[single shot]

Simple but complete information.

All I can think to add is:
If shooting cast bullets, get a LEE LEAD TESTER. It is simple to set up and operate. And it has a chart that tells you how hot you can load a particular tested lot of bullets before you get gas cutting of the bullet and leading of the barrel.

[jim4065]

I just ordered a Lee hardness tester from Midway. Is there any kind of "offset" or accommodation to the use of a gas check? It would seem like the GC has to cut down on the amount of gas blowing past the bullet, thus allowing a softer alloy with a given speed or pressure. After reading version II of Lee's book, it seems like Lee is ignoring bullet diameter, slugging the bore, and all of that. I like the correlation between hardness and speed that he developed, but I'm now getting the impression that his answer is only part of the story.

[kodiak1]

Using a gas check will let you push a softer bullet faster to a certian extent. Anything faster than 2000 fps and I would want to make sure that I was using a little harder bullet mix to aid in the bullet hanging on the the grooves of the barrel better and to also aid in the bullet to hold up on contact (hunting) to do max damage in the wound channel.
Ken.