I am assuming this is for a muzzleloading rifle?
As a side note;
Conical 'balls' did not become popular for SXS (double barreled) black powder rifles until they were contained in a ctg. case. Thus being contained and of groove size, they could be made from hardened lead.
There was and is a real danger of slippage forward of the unfired bullet which would then constitute an obstruction - as well, the pure lead needed to ease loading and give acceptable accuracy, reduced penetration to less than that of a hardened round ball. Thus, until the elongated bullets could be made 'safe' and be comprised of hardened lead, the round ball was the best projectile for big game rifles.
Samual Baker wrote "I have rifle that never failed to stop a charging elephant. I had a 3 ounce conical mould made for that rifle and it led me into such scrapes that I eventually gave up the conical as useless". A ball of that size (14 bore), hardened with tin or mercury, driven by 4 1/2 or even 5 Drachms of powder, would penetrate through and through an elephant's skull."
Verl Smith or NEI comes to mind for Paradox-type bullets - any custom bullet mould maker.