Phil, I have been using the Lyman iron molds for years; I still do when I want those beautiful Keith bullets. At first I left the bullet in the mold just as you do. Later when Midway USA came out with their Frankfort Drop Out mold release I started using that. No trace of rust using the Drop Out and I start getting good bullets once the mold comes up to temp.
http://www.midwayusa.com/viewproduct...tnumber=763758
For the Lee molds, I've found that they work best when properly smoked. I wonder if the casting temp has some type of curing effect on the aluminum as it seems to on the iron mold. I always grease the hinge points and the locating pins with Alox prior to casting because the mold seems to work smoother. I don't leave bullets in the aluminum molds or even use Drop Out in the cavities though I do spray some on the steel sprue cutter plate to prevent rust.
Know what you mean about casting so many bullets that you could use up all the primers. I cast during cool weather and usually knock out 500-1000 bullets at a session. The 6 banger makes quick work of that project. That leaves me time to scrounge for lead.
I cast for .32, .38, .44 and .45 Colt and ACP with soon to be 9mm. One thing folks on the forums recommend is to get as much lead and wheelweights as we can right now cuz the EPA is going to squeeze our hobby right out of existance.
Good shooting!
Charlie