I agree somewhat with longwinters - I would choose a Partition any day over an Interlock. If you load the 7mm Mag to its potential it will push the 139-140g bullets to 3200fps, and that, IMHO, is too fast for standard "cup and core" bullets.
In my order of preference at velocities over 2900fps:
1. A-Frame, Trophy Bonded, North Fork
2. TSX, XLC
3. Partition or Grand Slam
At 3200fps I would stick with bullets from lists #1 or #2.