You gotta be twist appropriate , tried 139gn hp boatails a friend swaged up specially for my 2506 and .257Wby, both on a 10 twist, unstable, worked out we needed 8, .270 the same for the heavier bullets, realistically the .277 150gn Berger and SST will kill anything we hunt out at 500yds no drama , if you are hunting Grizzlies, get a bigger gun.
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