I've only killed a couple of deer with Sierra bullets, but they worked well for me. The first was at 355yds with an 85gr HPBT out of a 240Wby running about 3500fps at the muzzle. Bullet went completely through and she dropped at the shot. Got the same result at 100yds with a 140gr ProHunter out of my 7mm-08 running 2815fps.
I also load the 65 SGK at 3500fps in my 9 twist 22-250 and the 63 SMP in my 223 at 2950. Haven't taken any game with either of those yet.
In other words, your impact velocities were around 2400fps for the 240WBY and 2570 for the 7mm-08. Not exactly blistering impact speeds, which is generally a good thing with lightweight cup-and-core bullets.
All the cup-and-core bullets I've shot through water jugs with a witness target a foot or two behind them have peppered the target with little shrapnel holes.
Not that it is a surprise - all the weight that is not retained goes somewhere...
