I enjoy shooting groups in my deer/elk rifles but my main concern is first shot out of cold bore for hunting and maybe 2nd or 3rd fast followup shots just to see how they print to first shot.
My varmint partner has 300mag Vanguard it's first gen like your. He shoot factory and he can do pretty good 3/4 shots and he'll let it cool some but shots start moving. I talked to him about having it bedded etc he said heck with it shot good on cold barrel. He took pretty nice 5x6 bull this year got him down on first shot took 2nd shot to finish he was good bull.