From this -
"The handloader can easily make cartridge cases by necking up and fire-forming cases from any similar,.532-inch base diameter, belted magnum: the .338 Winchester Magnum, .308 Norma, etc., or by shortening and forming longer belted magnums.
Norma continues to make factory cartridge cases in this caliber. One advantage many handloaders enjoy is that the bore, being .358-inch, allows use of the vast variety of relatively inexpensive bullets designed for the popular .38 Special/.357 Magnum handgun cartridges to be used for plinking, hunting small game and vermin, and lower-recoil target practice. Light (lower power) loads with bullets designed to expand at lower velocities, that emulate lesser cartridges such as the .35 Remington or .358 Winchester, can also be handloaded for use on deer and other smaller big game, something that cannot be done with the .338's and .375's for lack of suitable bullets."
If you're into wildcatting - it looks like this wouldn't be too much of a change, for either you or a competent gunsmith. And, if you can get the cases from Norma, handloading would be quite easy.