I have a Lyman's 49th edition. It lists a max 15.2 grains of 2400 for 1501 fps in a 14" barrel - the same as the 47 edition. Probably no testing was done on this cartridge since the 47th came out. I have found that Lyman Reloading Manual to be conservative and do not use it for jacketed bullets. I do use it for cast/lead bullets. You should always start at the low point and work your way up. The max is different in different manuals. This is caused by many factors. The chamber size, the bore size, the rifling depth, powder lot, primer used, jacket thickness and on and on. For the top load, I generally look at 3-4 big name manuals and then try to match the componets as close as I can to one that looks promising. I run my loads over a chronograph. When the selected load approaches the same velocity as the max load, I call it good as long as I do not go over the max load. As I work my way up through the load range, I watch accuracy. Many times the best accuracy is not at the top, but some where between the bottom and the top. If you find that the best load is somewhere below max, you will need to limit your range accordingly. If you have a 200 yard gun/load and you are 200 fps less than max, then you may have to limit your range to 150 yards, for instance.
The bottom line, there are so many variables, you just have to use manuals as a guide and find your best load for your gun.
One more thing, be very wary of loads found on the internet. Some people push the limit and then add a little more above safe levels because they want to get the most velocity they can or more than anyone else gets. Also - with the 357 Max, more recent loads were reduced because of gas cutting on revolvers in the early days. the gas cutting was worse the less the bullet weighs. Of course you do not have to worry about gas cutting in a T/C, but you still need to be cautious. If a reliable manual says you will get 1500 fps with a certain load, and you up the load and are getting 100 fps more, you are over the limit....be careful.
Good Luck and Good Shooting
