I would add check your case capacity with a 120 and water. Then look in Nosler data if your capacity is the same as 6.5x284 that would be about max
You're only off by 17.5%
Per Nosler:
260 Rem (reg) + 120 bullet => 47.8 gr H20
260 AI is 5% bigger, so => 50.2 gr H2O
6.5-284 + 120 gr => 59.0 gr H2O
but thanks for playing the game . . .