Thanks for the replies...I went and did some reading and understand what has been said.

47.5 gr of 2209 gives me 2770 fps. I suspect some of this is my suppressor.
42 grain of 2208 gives me 2690.

I actually fit the 2209 but have deformed the projectile a little in the seating process so I'm close to being viable. Using Winchester rather than Lapua helps a little and I can look at settling the powder better in the case.

I'm sure I'm being anal worrying about 70 fps. I've also yet to fully explore accuracy but initial results suggest 2208 might be best with the best 2 shot group under 1/2 moa while the best with 2209 is just over 1/2 (Savages rule).
(I use 2 shot groups because the Stevens consistently opens the group on the third shot...works for me)

I think I'm giving away a little accuracy going from 140 BT's to the 162 Amax but I think they should kill better at 600 yards.

All the best...Chris