what kind of lube are you using? are you powder coating. a Glock? I'm guessing 9mm or 40 s&w. I'm no expert and dont powder coat but I do believe some folks that powder coat have reported using pure lead powder coated you might not have any problem with your Glock.. others have given suggestions to harden pure lead, add monotype or foundry type or something like rotometals hardball.
here is an article you might find as a good help
http://www.lasc.us/CastBulletAlloy.htm