I run one of your so called "no sense 20 inch" barrels in 1 in 10 twist. 185 berger juggernaught at 2600. 5500' at 25° It doesn't go sub sonic till 1360. Even at sea level I'm super sonic to 1120.@25°.a 308 will take game at 600-800 or more, wind drift will be your problem with a 308 more then anything else. With any cartridge for that matter. I've always found that if you can make good hits reading wind with a 308 when you step the game up to a hi performance round making hits just come all the easier. Making consistent hits in wind with a 308 at a 1000 takes work, with a big 338, 7mm, 300 mag ect... even most 6mm's and 6.5's *it's like cheating.