The cartridges with the multiple shoulder were the brain(?)child of Jaques Herter. Wild claims were made for them. Since chronographs were rarely seen, wildcatters were able to make claims with little concern that anyone would check it out.
I always figured the 7x61 S&H was derived from the 275 H&H which was nearly identical. Although not quite able to match 7mm Rem Mag performance, it was still a pretty good cartridge.
During the course of my career, I probably chambered no more than three or four 240 Weatherby's. Performance was closer to 75 to 100fps over the 6mm Remington if all else was equal. Still, it was an interesting cartridge.
Any discussion of forgotten cartridges has to include the cartridges designed and chambered by Charles Newton. The 256 Newton (really a 6.5mm), the 30 Newton, and the 35 Newton were all cartridges which were thoroughly modern in design. So much so that the 30 and 35 were reproduced with a belt and became the 308 and 358 Norma. If Newton had not been at odds with Winchester and Winchester had elected to chamber for his cartridges, we would never have seen the 300 H&H in North America. We would also have never seen the 338 or 300 Winchester magnums. Winchester might have elected to neck up the 30 Newton to 375 just like Ruger did and the 375 Winchester African would have been born.
The 256 Newton provided the impetus for Winchester to produce the 270 Winchester. The 256 is a slightly shortened 6.5-06 and the original loading drove a 129 grain bullet at around 3000 fps. Today, it would still be a great performer. GD