I was getting not marring but a draw burr... the rivet head material would pull into the gap between the puller hole and the rivet nail. A piece of aluminum with a hole to fit the nail fixes the problem and when you use it it gets a little mashed so the hole gets tighter rather than looser.
Also I ground material from the puller for corner clearance.
John Bright, RV-6A, at FWF
Conti Titan 360, 8.5:1, vert sump, SDSEFI EM-5, inj in inj ports.
Z-12/SDSEFI dwg ECUdual4.
Newport News, Va