Thats only lead, you need to clean that ASAP. You will need to becareful not to scratch the top finish off or the bottom frame.....
Don't scrub too hard, you will need a brass brush, lots of oil to remove that caked on stuff. I try to wipe mine down before I leave the range, if not its very hard to remove. I usually use a knife to pull/push/pry the caked stuff off.
When I used to go through a whole box of 550 in my Taurus 94 in 5 hour range session, the lead build up was more than that.