For reloaders, shares many of the same powder types typically used for reloading heavy pistol calibers (357 mag, 41 or 44 mag, etc). In my case, already had a 4 lb jug of Enforcer which has been my go to powder for both 357 and 44. Worked good with the 165gr FTX and was able to develop a 1" MOA load.

Lil Gun, which is somewhat available, also works for 350 legend and it's big brother 450 bushmaster