I tried both 308 and 260 brass to make 6X47 Lapua. This issue is 2 fold. You have to move the shoulder back a bunch and it will tend to fold in on itself and you have to squeeze a lot of neck down along the way. My success rate was about 40% give or take. Then I tried 6.5 Creedmoor range pick up brass. Guys were firing it once and giving it to me free. My success rate went up to close to 90%. The shoulder is already 30 degrees which really makes it easier.
Redding imperial wax is the best. I also found that I had to take about 4 draws on each case. I would do just a little, then retract the handle, pull the case out and re-smear the wax around always making sure that it is very thin. Between each case I would take a q-tip and clean the shoulder area of the die. I found that the folding was somehow started by having a little too much wax.
I don't know about the Lee case forming dies so I cannot comment. I was using a Whidden bushing die with different size bushing along the path.
You aren't out of the woods once you have what looks to be a pretty good cartridge. I had a few when loaded had horrible runout after being fireformed and then resized. Those went into recycle. But now I have a set of practice brass that I cannot tell the difference from my Lapua match sets at 100 yards. I also have a free back up of another 200 cases or so when these start giving up.
David