My M&M 500 (as seen way above!).
Neither have I come across any mention of Leech and Rigdon producing bullets--no mention in Edwards' "Civil War Guns," in his Leech and Rigdon discussion on pp. 352-353.
Well, based on all of the above thread (and an enjoyable one it is/was) I've decided to keep my M&M 500 amongst my Confederate bullets, but with the following note in my "catalog":
".36 caliber, possibly for Confederate Leech and Rigdon six-shot revolver per Bill Ewing (see NSTCW, Vol. 28, No. 2/2001, p. 33, and
www.cwbullet.org)--but Jim Thomas, through his research, believes these M&M 500s to be variants of M&M 99 and also produced at the U.S Arsenal in St. Louis (see
www.cwbullet.org). This bullet measures .385 diameter, .590 length. There may also be variants of M&M 500 (collector CraigC in PA reports a .39 variant--see
www.cwbullet.org), M&M 500, T&T 38B, C.S.A., dug near Richmond, Virginia."
As always, I am open to comments and critiques.