Here is something on the 284
NBRSA 1K Winner Jerry Tierney
Record-Setting .284 Win F-Classer
I own both 284 and 280AI both have 27" Lilja 1/9 twist barrels and they are just hunting rifles
in the 284-- 53gr/R-17 with 160gr Accubond @ 3048fps
in the 280AI--56gr/R-17 with 160gr Accubonds @ 3046fps
I haven't shot any Berger bullets yet in either rifle. OAL length on my 284 is 3.100" so I have plenty of room for those longer bullets.
What I do is e-mail Walt at Berger and see what he thinks would work as he gets more feed back on his bullets and I'd ask him about the 284,284 Shehane,280AI,7WSM.
Well good luck