I use tumble lube bullets almost exclusively. I shoot .41 mag at 1300 FPS with no problems of leading. I shot some .357 yesterday at about 1200 FPS out os a 6 inch revolver. No lead. I was using AA#9 which happens to be my prefered powder for magnum loads both jacketed, and cast lead.
No matter how many times you do it and nothing happens it only takes something going wrong one time to kill you.