Starting with Buffalo Bore data at:
Heavy 357 Magnum Pistol & Handgun Ammunition
2. 4 inch S&W L frame Mt. Gun
a. Item 19A/20-180gr. Hard cast LFN = 1375 fps
then using balistic calculator at:
Handloads.Com Ballistic Calculator
Range Velocity Impact Drop ToF Energy Drift
0 1375 -0.5 0 0 756 0
10 1341 0 0.14 0.02 719 0.48
20 1312 0.32 0.47 0.05 688 0.61
30 1284 0.43 1 0.07 659 0.83
40 1257 0.32 1.75 0.09 632 1.14
50 1232 0 2.71 0.12 607 1.53
or 607 ft-lbs at 1232 fps at 50 yards for the 180 grain hard cast by Buffalo Bore