bb'
i think Datil gave you a good answer. i don't remember the Starline brass splitting 'episode'. but i do believe that paying less for .357 Max' brass from Remington, and then trimming it to .360 DW length may be a reasonable option, particularly since it picks up some velocity over the .357 Mag' but does not make the bullet jump the same distance as the Maxie' does before engaging the rifling. that may help Some with accuracy, but how much i can't say. every rifle is an individual unto itself.
one more thing, however, if i may. considering that you can readilly buy Maxie' brass right now, why not pick up a bunch of it, chamber the rifle for the Maxie' and use your .360 DW brass (if you should already have some) with some real slow powder for "the kid" you mentioned in your one post. if you use something like Win 748 or IMR 4320 (which meters very well from a measure) in the .360 brass it will develop less velocity and pressure while giving you great loading density with good, consistent ignition i'd expect. with Win' 748 you'd need a strong primer to get that ball powder ignited well, particularly in a straight-walled cartridge. and your crimp needs to be pretty firm as well.
take care,
ss'