I shoot cast in my 8x56R guns. Some work well with the Lee 0.329", but for the others, I bought a custom Lee 0.332" lube-sizer and size down 0.338" cast bullets. 6-8 thou is about the limit for sizing down.

For cheap jacketed bullets, try the Speer Hot-Cor 338 sized down to 329 in a the Lee sizer. Use lots of lube and go nice and steady. This method will not work with all bullets - only those with a thin jacket, like the Speer.