I would probably just run Starline through your dies to neck it up and fireform with .358 pistol bullets. Same amount of work and noise as the COW method but you can plink at rocks or something while making the noise. If nothing else it’s trigger time with your new rifle.
I like the Cream O' Wheat method, but given the availability of cheaper pistol bullets of the proper diameter, I have to agree with the Kid that this is the way to go. A pistol powder in the Bullseye-to-Unique burn range is your friend.
