I have been shooting the Lee for some time. The bore size is NOT a problem, however, SOME cases seem a bit thick and cause them to chamber tight. I have not had any problem with Starline, but some of the Magtech brass was thicker on one side. I would bet that you can drip lube them and they chamber without force they will shoot just time. I suggest you crimp them just enough to take any bell or flare off the case mouth. Since I use my sizer to lube mine anyway it does not matter, but there is very little sizing that takes place as the bullets are just about diameter to start.
I have recently found out that Lee also makes an "Improved Minnie Ball" mold that is .500 dia that is used in muzzle loaders, it is 360 gr. I purchased one, but have not had time to test it yet, I plan to use it as a plinker load. You might want to check that out also.