The 375 grain shot excellent in a number of my inline rifles. And also in my Green Mountain Barrel fast twist. In my Black Diamond XR they shoot excellent. But I found I have to push them kind of hard. A forum member years ago that also owned a Black Diamond XR booked an elk hunt in a state were only lead projectiles could be used. I suggested he try the 375 grain SSB, which he did. He found them liking 110 grains of Triple Seven 2f and was able to drop a large cow with them. Although as I remember it was about an 80 yards shot he said, and she only took and ran a very short distance.
The 270 grain ball-ets shot real good out of my Knight LK rifles. With about 80 grains of powder. In fact a person's son uses that same rifle every year for muzzleloader deer, and has never had a problem that I know of ... taking a deer.
I know a lot of you are into the brass and copper bullets, and that's fine. But in all honestly, I never had a problem killing a deer with an all lead bullet. Where that was a roundball (and buffalo bullet used to make some excellent roundball) or lead conicals.