I agree with Flags, among others here! Two thins here that are B.S. #1 Bullets CANNOT go "too fast" to expand! Faster velocity= faster expansion.
#2, With the .300 WSM, 180 Partition shot, it would not be the bullet's "fault!" While the .300 WSM and the Partition is definitely NOT "over-kill" on a hog, the problem is likely that a double lung shot, with a tough bullet may not have met with enough resistance to guarantee good expansion. A good, tough bullet has to hit "something" to expand! Thread one through the lungs, missing rib bone, the bullet may not get good expansion. I've bang-flopped 300 pounders with 100 gr. Partitions, so any good bullet in .243/6MM on up will do the job!