I had similar issues with cast bullets in both .45 ACP and .38/.357. With the automatic the leading problem was solved by pushing the load a bit harder. I didn't want to push the .38/.357 so I ordered some slightly softer bullets from Missouri Bullet. I use their IDP#1 (hard cast) for .45 ACP and their .38 Match for the softer loads.
Missouri Bullet Company
I hope that helps,
Frank