The M-624 Smith & Wesson is based on the N-frame and is considered the strongest of the S&W revolvers excluding the X-frame chambered for the .500 S&W cartridge.

Any load remotely appropriate for the .44 Special is certainly safe in the N-frame S&W revolvers, through the years I have shot many rounds in the 1100 fps range with absolutely no issues in my M-624.

One has to remember that this is the same frame that the .44 Magnum is chambered in and has twice and more of the operating PSI of the .44 Special.