Interesting subject, humans clocked at max velocity between 110-120 mph before opening their chute. Because of atmosphere you quit gaining velocity at some point depending on your ballistic coeficient and I don't know what a 300 grainer is traveling backwards or wobbling. In a vacuum it would continue gaining velocity at 32 fps per second squared. So the higher you dropped it the faster it would be going when it hit. But atmosphere prevents that and all objects max out at a certain velocity with most solid objects clocked between 100-130 mph.
At 150 mph if it could reach that it would be 220 fps and I would not want to be the guinea pig hit by a 300 grainer at 220 fps. I think that could cause enough hemourage on the brain to kill somebody. 120 mph I think is around 165 fps. I wouldn't want to get hit in the head with that either. A 300 grainer hurts just dropping it on your head. Thus my point I always try to make. Always shoot a heavy large caliber bullet at large big game long range for best results. Drop a 168 grain 7mm or 140 grain 6.5 mm on your head and then a 300 grain 338. You will get my point.