Ive settled on these loads, using an MEC 600 and 700X. Works fine for my application.

Winchester AA
Win 209
CB-1100-12 (WAA12SL)
1 oz
13.3 grains of 700X
5780 psi
1080 fps
Bushing #22

Nitro27
Win209
CB-1100-12 (WAA12SL)
1 oz
15.0 grains of 700X
6300 psi
1100 fps
Bushing #25