The load used the weaker 45 auto rimmed case, 14 grains of 2400 and a 255 grain lead SWC. This is off the top of my head, so if you can't confirm it, don't use it. The writer claimed 1200 FPS from a Smith & Wesson 625 chambered in 45 ACP.
The following is from an older RCBS manual I have,
CAUTION: The following post includes loading data beyond currently published maximums for this cartridge. USE AT YOUR OWN RISK. Neither the writer, The Firing Line, nor the staff of TFL assume any liability for any damage or injury resulting from use of this information.
____________________________________________
from RCBS Reloading Guide (1973), page 44
Sixgun Loads
By Elmer Keith, Shooting Editor, GUNS & AMMO Magazine
IMPORTANT
Here are a few important rules to follow before attempting the following loads.
1. Full Length size cases in all calibers so they will hold a bullet so firmly that you cannot turn it in the case with the fingers before the crimp is administered.
2. Use a full heavy crimp on all revolver loads so bullets cannot jump forward.
3. Cast bullets should consist of one part tin to 16 parts lead (unless otherwise indicated).
4. After casting, size all bullets to the exact groove diameter of the particular gun.
5. Pistol powders are usually fine grain and it is imperative that you carefully weigh or throw the powder charge.
.45 AUTO RIM
The Ideal #454424 cast bullet (cast very hard with one part tin to 10 parts lead or pure typemetal) and sized to .451" for Colt and S&W 1917 revolvers and the S&W 1950 target models. For "big" loads use the auto rim case and 14 grains of 2400 powder to push the bullet. Four or 5 grains of Bullseye or 6 grains of Unique using the same bullet make great light loads.