[AGE]

RK,

Obviously new brass is nice, but unnecessary for most purposes (except maybe benchrest matches or perhaps varment loads).

For very accurate rifle ammo, use new or matched brass fired the same number of times. One thing I haven't seen in the above responses is case trimming. For bottleneck rifle rounds you MUST trim the necks after every few reloadings. I do it every time. Cases grow up to .030" or more in length every time they are resized. If you jam a long neck into the rifling--WOW! Lots of excess pressure. Don't do it.

Pistol brass lasts for many reloads, you shoot lots of pistol ammo, and it is easy to loose brass from a semi-auto. Therefore, I use pistol brass until it cracks (maybe 10 or more loadings) and I scrounge brass wherever I find it. That said, for match ammo I do sort and cull the brass carefully.