I tried some 170 grain Oregon Trails silver alloy cast bullets with gas checks in my Winchester 30-30. I loaded them up at jacketed bullets velocities just to see if they would lead up the barrel. I'm not getting any leading and they are accurate. But wow, do they ever smoke. They're not quite to black powder levels, but there's definitely far more smoke then usual. My guess is that it's the lube burning up at those velocities.
I wonder if anyone else has tried them and got the same effect