A couple thoughts here, if you buy any factory ammo with jacketed bullets or load any and shoot them in any of these guns, you need to clean the copper out, completely or you will have troubles. Copper fouling likes to grab on to lead. Just for anyone who don't really know how to clean this heathen stuff out, get a bronze brush and a good copper solvent, I like Sweets 7.62, but there are some other good ones. Wet and brush and run clean dry patches through it till they come out with out any blue or greenish gunk on them. Then run a wet on through and let it it for an hour or so, then run a dry one through.
Most likely you'll have that gunk again. Keep at it with the brush and soaking till you get not the slightest trace. There that will teach you not to do that again.
Also to really get good results you need to get a scale that will weigh your bullets, unless things have changed, the lee one won't do it. How ruthless to get is up to you, but remember a #8 shot weighs right at a grain, so any under your standard will have a void(s) the size of a #8 shot. Myself I won't shoot anything that has a void that big I can see, so I also won't shoot one with a void that big I can't see.