Standard three wraps of wet onionskin (.002") paper will add 10-thou to bullet diameter.
You're going need a mould dropping at ~ 0.302 to start with.
https://thefiringline.com/forums/sho...61&postcount=7
Thicker paper/two wraps is problemmatic
Were I you, I'd consider that a 308 mould will probably drop at 310; PC it; then shoot unsized