My 320 is a bit over half inch for 5 shot groups at 50 yards, with Simmons 3-9 variable as I recall. Have never tried multiple ammos in it, just Wolf Match, CCI std and prob WW Super X HP. It does shoot better than my 69A, but perhaps not better than recent 72A, which likes CCI std.
They are a well made rifle and I like mine. Found it under $200 over 10 years ago with no mag, and LGS did not want to chase a mag. A lucky day for me. And found mag easily if not cheaply.
Good luck. Remember, such a purchase is just a conversion of assets, not a throwaway! (What I tell myself.)
Regards,
Dyson