I've got a Stiller Predator long action magnum bolt face coming from a group buy, still trying to decide on chambering. It would get used when I go out west to hunt, usually every year. I've got sporter weight 7mm and 338 RUM's and a 30-378 Accumark. I'm leaning towards a heavier platform, either an A2 stock or a PSS like on Shawn Carlock's Canyon rifles with a varmint contour barrel and a brake. It would be a repeater with a Wyatt's mag box. Wonder what kind of velocities the 338 RUM would get out of a 28" barrel with 225 Accubonds and 300 gr SMK's? Any other suggestions on possible cartridges?
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Since you already have a 338 rum, will that action work for a 338 LAI, or a 338 Allen express, he was also working on a new 338 above the AX BUT BELOW the AM I believe, as you are planning a little heavier.
Give the 338AM a try, or now that Hornady is making a 416 BTHP, go for the 416AM.
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you may like the 7mm STW. I don't own one anymore but I really liked mine. or if you really want a wizzz banger go with the 6.5 STW. I'm in the 6.5 craze right know and if you don't own one you should.