Dwight; I have a few of the CBC 28ga brass shells (ones with berdan primers). I believe newer ones are available with LP primers. These have an ID of about .580 near the mouth, didn't check them all the way down, but don't think they vary much. If using card & filler wads these would require oversize wads, (24ga I believe) available from Circle Fly & also Grafs I think. These hulls should take 3/4oz with equal volume BP (about 1 3/4 drams) with ample room for a good wad column. The Rocky Mountain brass is turned from bar stock & has thicker side walls for regular size wads thus less internal capacity. They are high quality I understand, but being turned as opposed to drawn renders them much more expensive as well.
