The sectional density and BC of a 130gr 6.5 bullet is significantly greater than that of a 30 cal 125gr bullet. I haven't run the numbers but at 500yds, the 6.5 bullet is going to penetrate deeper, and drift a hell of a lot less in the wind.
I'll use the 125AB in my 30BR, but not in any cartridge I expect to shoot past 250yds.
