JHT: You can go all the way to 250 gns in the 35 diameter bore but I think that weight slug is too heavy for the 357 Max. You can use 200 gn slugs, either cast or jacketed - the jacketed are for the 35 caliber rifles and may or may not expand properly on your target; the 200 gn cast shopuld not expand at all. I would think you could successfully use any bullet weight available in 158, 168, 180 or 200 gn; couple of places sell 200 gn cast semi-wadcutters.
But I didn't understand your statement 'not to cut the strap'. Whazzat mean??? Mikey.