I generally use 8-9 oz. topgrain cowhide for unlined holsters. For lined holsters I will use 6-7 oz or 7-8 oz. for the outer layer with a 2-3 oz topgrain cowhide lining, smooth side to the gun. I try to keep the total thickness for lined Western holsters in the 8-9+ oz range. For hunting holsters I will go to 10-11 oz. total thickness. Note that all leather must be vegetable tanned. NEVER use chrome-tanned leather for holsters!