I anticipate another "myth busting" thread in the future - lead vs coated bullet accuracy.
Between down pours of winter rain, I have resumed my jacketed and plated bullet testing with Glock 22/KKM/Lone Wolf barrels and 17" Just Right (9/40/45 barrels)/16" PSA carbines.
I am starting a comparison reference database for bullet/powder/OAL with corresponding chrono data and 25/50 yard 10 shot group accuracy for the inevitable "Mother of all bullet comparison" thread which now will likely include coated bullets.
As to lubed lead vs coated, I think what Glen Fryxell discussed in chapter 5 of his book is pertinent to our discussion -
http://www.lasc.us/Fryxell_Book_Chapter_5_Lubrication.htm
Coating on lead bullets simply act as a lubricant which allows gas leakage around the bullet while lube can act as both lubricant and "O-ring" sealant to better trap/reduce gas leakage to produce more consistent chamber pressures and greater accuracy.
"The fluid dynamics of lube flow has many components: simple displacement, compressive pumping, linear acceleration, radial acceleration, and pressure-induced pumping.
When the bullet is engraved, the lands displace not only bullet metal in the driving bands of the cast bullet, but they also displace a certain volume of lube in the lube grooves. This displacement serves to compress the lube somewhat, thereby forcing it into contact with the rest of the bore, as well as into the nooks and crannies of the bullet/bore interface.
This is the first and simplest lube pumping mechanism. As the pressure builds, the force applied to the base of bullet may grow to the point that it surpasses the compressive strength of the alloy. At this point the central core of the bullet in the lube grooves is compressed, getting fatter and shorter, which in turn reduces the volume of the lube groove. Once again this compresses the lube within that groove and forces it to the bullet bore interface."