Another Unique and 2400 guy here, with about 30 years using them in the 357. With 6 Gr Unique and 13.5 Gr 2400 under a 158 Gr LSWC, you pretty much have everything covered that a 357 Magnum will do. The Unique load is at around 1000 FPS and the 2400 is at about 1200. They changed 2400 a few years ago and 13 grains will probably give the same velocity as 13.5 used to. I haven't chronographed any 357s with the "new" 2400 yet, but it does produce higher velocities in other calibers. I shot a lot of the big Upstate NY tree squirrels with the Unique load, back in the 80s, with my 6" Security Six.

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Tom
"Panem et Circenses"