I've been asking for a .310 190gr SPRN from everyone. Other than Contract Custom I've found nothing that isn't cost prohibitive to me.
Begs the question, "why .310" bullets?"
Because that was what the Savage was designed for. .308 bore, w/ .310 "tight" fitting bullets. If you mic. early ammo you will verify for your self. Or read West's book. Increased pressure, increased performance
Ammo makers got sick of carrying spl. pills for Savage and either dropped them or loaded with .308 pills, thus dropping ballistics to a 30-30 twin
Also, rivalry between Companies was huge then. Savage never loaded their own ammo. If your competition can turn a profit making your ammo, plus kick you in the ballz by reducing its ballistics, red letter day for them.