I started shooting 139 grain Hornady Superformance 7MM Rem Mag this year about midway through the season. I killed one deer with my old .270 using Winchester Super-X (lead tipped). Results:

.270 130 gr Winchester Super X (lead tip) 280 yards - Big bodied 9 pt, great shoulder shot, deer ran 90-100 yards with no exit wound and didn't leave a blood trail for the first 25-30 yards.

7MM Mag 139 gr Hornady SST 336 yards - Bigger 8 pt, same shot placement, didn't flinch and dropped. No exit wound. Had to drag him over 300 yards and he never bled a drop.

7MM Mag 139 gr Hornady SST 58 yards - 100 lb doe, same shot placement, turned her a barrel roll flip. Never seen that. Deer had blood wrapped around her like a band from the flip. There was a solid string of bright red blood for about 10-15 ft past her. Not drops, a solid line. Bullet obviously never expanded. Hardly lost any velocity. Downfall of 7 mag. She did twitch for a few seconds on the ground, but didn't get up of course.