I would not use the hot stuff or factory ammo with the Shadow as sprung.
However, both Atlanta Arms black box as well as Corbon Natch line of ammo come in 147 grain Match loads that should be OK to use in the Shadow.
I know that Angus recommends a 124 load. If you plan to shoot 124 grn ammo, just follow the book & use the starting load for N-320 & a JHP.
If you absolutely refuse to reload, then try to find some Commercial Reloads like Atlanta Arms blue box - it is loaded lower down close to the power factor.