I cast all my own handgun and rifle bullets. I shoot cast in 9 x 18 Mak. 9mm,38/357,45 ACP and in rifles 30-30,300 Sav. 7.62 x 39 and 54r.
Under normal circumstances leading doesn't have to be an issue,I only have one revolver that slightly leads due to the leads in the forcing cone being a little rough. It's a new gun and with some shooting over time that will take care of itself. Removing those lead flakes basically entails running a wet patch of Kroil Oil down the tube letting it set for about 30 min. and brushing it out with a bore brush wrapped with a tight fitting patch.
In the gas operated guns leading is not really an issue as long as you don't go through a lot of extend rapid fire secessions and super heat the rifle. One the gas piston type guns like my SKS rifles I can shoot a couple hundred rds. before fouling builds up on the face of the piston. That is easily removed using Kroil Oil,AFT fluid or Marvel Mystery Oil and some fine steel wool,coating the gas piston and inside of the gas tube with ATF or Marvel makes subsequent cleaning later much easier.
Here is a good explanation of leading and it's causes as well as how to keep it for happening in the first place. Click on the TOC bottom left and you can see the entire web book and download it for free if you like.
http://www.lasc.us/Fryxell_Book_Chapter_7_Leading.htm