In my Marlin 1894CS, loads put up in .357 brass are more accurate than those in .38 Special hulls. I've loaded a hellofa lot of cast bullets, gas checked in both types of brass using, Unique, 2400, Ac#9, 231, and Herco and the .357 brass is always better. Same with Hornady's 158 gr XTP, Remington's 158 gr JHP, and Sierra's 158 gr JHP, the .38 Special loads are never quite as accurate.
In magnum brass, that carbine is good for ~1" gps at 50 yds with either the cast bullet or Hornady's 158 gr XTP. At 100 yds, the Hornady is always a bit better than my cast, but not by much. Either will do 1-1/2" gps for the first three shots, using magnum brass, off a rest with a 2.5x scope mounted.
HTH's Rod