Have had two instances of bizarre deflections over the years, both with 243.
The first was a fallow doe shot in the shoulder from about 30 yards from a high seat using factory 100gn soft point ammo, the bullet turned 90 degrees & exited to the rear.
The second was a fallow fawn about 100 yards away shot from a quartering away position with the intention of the bullet going into the ribs ahead of the diaphragm on the left side & exiting ahead of the shoulder on the right side (it was the third shot in a group). The entry was exactly where it should have been but the exit was ahead of the shoulder on the left side - the bullet obviously had some ‘spin’ imparted on it as it hit a rib on entry & deformed. Fortunately it did enough damage to prove fatal.
The bullet in the second case was a 105gn Speer spitzer, I only loaded up one box of these bullets as although they were very accurate in the 1:8 twist barrel I had some unexpected results with them - mainly not expanding, so they went down the range & I reverted to Sierra 100gn pro-hunter.