.725 is a standard 12 gauge round ball mould available from many sources in the US or from Jeff Tanner. And as noted you can even buy off the shelf .725 pure lead round balls from Ballistic Products to do your development loads (or play) as you wait for the mold and molding process to make your own.

Also, at 20 yards on a grizzly I would actually take a double barreled hot .725 pure lead round ball load OVER a bolt action 375 with round nose bullet. Certainly WW (wheel weight) round balls would be even better but the big, heavy and heavy smacking big heavy .724 - .725 diameter round ball loaded up hot is potent stopping medicine for sure.

Just for "comparative consideration" and certainly NOT an indicator of straight apples to apples comparison---the .725 dia round ball is going to weigh in at a collosal 570 grains (plus or minus a tad) while the 375 bullet will weigh about 350 grains. For 20 yard stopping power bring on the heavy weight I say.