If it's a new gun, the answer is easy. Cimarron Lightning in
.41 Long Colt.
http://www.cimarron-firearms.com/Spe...-Lightning.htm
I have yet to see a LGS that stocks .41LC, and the price of new ammo and cases will make your jaw drop.
http://www.midwayusa.com/product/687...-bulk-packaged
http://www.midwayusa.com/find?&sortb...ensionid=10103
Furthermore, AFAIK bullet casting molds aren't even made for this cartridge, probably because of the inconsistent bore diameters used by Colt. The cartridge was originally loaded with a heeled outside-lubricated bullet, but Colt later switched to a smaller-caliber inside-lubricated bullet with an expanding base, but they apparently never firmly decided what caliber to use*; their later revolvers were reportedly built with a baffling array of bore diameters.
AFAIK molds used to be produced in several different calibers- the shooter / bullet caster was expected to slug the bore and match the mold to the individual gun- but as the cartridge fell into obsolescence, the molds were discontinued, and people now have to custom-order .41LC molds.
*Footnote: Firing undersize .41LC expanding-base bullets in oversize bores never worked very well and gave the cartridge a reputation for "can't hit the broad side of a barn from the inside" accuracy; this is often given as the reason why the cartridge was eclipsed by .38 Special and fell into near-total disuse.