Its sort of funny that light weight bullets are what everyone wants to shoot because all they are concerned with is velocity. I have a book called "The Selected Works Of Finn Aagaard" and he has a couple of chapters on the 6.5 cartridges. There were several in use around the turn of the last century. It was a popular bore size for the armies then switching to smokeless powder rounds.
The early rounds all used bullets in the 150-160gr range. They gave deep penetration and were even used on Elephant. A 120gr bullet would not be a good choice for that animal. The heavy bullets gave deep, straight penetration and most of those African hunters preferred the FMJ bullets to prevent bullet break up. Something they really wanted to avoid. The early 6.5s also only shot around 2300fps. But most of the shots they took were 200 yards or less. I guess they were better at being hunters and didn't consider longer shots. Plus most all the rifles were open sighted. Those heavy bullets made the reputation of the 6.5 bore.