Zr600 try RL/26 with those B/150s lots and lots of great reports about it in 270s with 150 GN bullets ,we are very lucky to have so many Great powders , true some bbls are slow some fast some in the middle mine weres a 24 in bbl a 22 will lose 50 fps or 25 fps per inch .granted the Barnes work but they loose ft lbs at longer range because of their liter weight , everything's a compromise , but then again short range it won't matter , ya se bbls like certain weight bullets but a good reloader will fine that out by testing n shooting !. I don't shoot factory I reload shame on the Factories for under loading so many fine Cartridges , just to make some look better on paper then others, reloaders arm yourselfs with knowledge it's out there prove it to yourself isn't that what really matters !!! Rifle case volumes vary ,primers & bbl lengths , but a smart reloader Gets it !!! & puts the puzzle together for His or Her advantage . Young shooters & Reloaders ask questions of your Senior reloaders n shooters like minds Gather , the best reloader I have the pleasure of knowing is 81 or82 yrs young he's Forgot more then Most know , TAP this resource before they are gone !!! Regards jjmp