I've used "bought" cast bullets before, not from MO but Montana, when I'm too lazy or in a hurry to cast some.
I don't know of anyone who sells cast 150 SWCs but most sell 158s. In reality there ain't a nickles worth of difference.
I don't change anything going from 150 to 158s.
In fact, I might just go to store bought cast bullets anyway, simply because I'm getting old(er) and more lazy.
CPT USAR Ret
USAMU Sniper School Oct '78
Distinguished Rifle Badge 1071