Mine has a 1/10 twist and with 120 grain bullets accuracy does not equal that of lighter bullets. I doubt this twist would shoot 130 grain bullets worth spit but could be wrong. Over the past 40 years I've had 3 different 257 Roberts and the one 257 A.I. R. Actually, none of them shot their best with 120's and the 120 Hornady HP was the worst of that weight. 87's and 100's were sub MOA and 120's were closer to 2 MOA
Not sure what twist you have but I suggest it shouldn't be a surprise if lighter bullets out shoot the heaviest unless you have a faster twist than 1/10.