I have a 26” 1-9twist barrel from carbon six 338 rum running the 285eldm at 2870fps with retumbo powder. I put the wyatts 4” mag box in it and that really woke it up. Can touch lands and still fit in mag. It is a great round.
I really, really like the Berger 250, I run them 3120 in several rifles with 28 inch barrels and they get where their going fast. They are extremely jump tollerent in rifles throated for 300's, same rifles run the 300 at 2830 with H1000.