"concerned with plugging up the gas port with bits of lead"
I have the same thoughts but the lead shooters don't seem to have problems. I have shot my share of lead in bolts and single shot rifles. Never built up the nerve to try lead in a Garand or M1A or AR/M4. But others do it. The sub-sonic boys are working hard with lead in the 300 AAC Blackout and aren't being bothered with gas block or tube problems (at least none are reporting any). They say it is like hitting with a brick