At 3200 fps with a 150 SP Interlock bullet (standard cup and core), it will have PLENTY of expansion. Probably too much expansion. If it's a full power load, the velocity should be more like 3300+ fps. What are you concerned about? Too much velocity?

I hunted with 150 grain .277 cal interlocks for about 3-4 years in my 270 Winchester with an estimated muzzle velocity of 2700-2800 fps. They were very expansive even at those relatively modest velocities, I had several with complete core separation and failure to go through and through. In my opinion the interlock ring is a joke as far as maintaining the integrity of the bullet. A 150 grain interlock at 300 win mag velocity will be a good SPLAT bullet.

They used to bee good but Hornady changed them and moved the ring forward next to the cannelure. Now they just expand over the ring and the core pops out. They used to be at the base of the bullet which held the core much better and built their reputation as a poor mans Partition.

These are 180 grain 30 caliber. Left is the old Interlock. Bigger ring and placed near the base.

In the end I think it will kill fine even up at the 3200 fps, it just might be a gooey mess and not the bullet performance that I personally look for.