i own a 1928 a-1. mine is a real tommy gun. when i got it, the guy who owned it had shot a lot of lead ammo threw it on full auto. i had some lead build up on the compensator vents. i removed it and was suprised to find it was loaded with lead on the inside. it took some really heavy cleaning with a brass brush to clean it out. since then i have only used jacketed 45 acp and have had no build up of lead. i don't know what kind of lead he used. soft or hard. nor do i know how well he cleaned his gun after use. kurt250