gnoahhh, you're not wrong for black powder patching. For smokeless make the finished bullet groove to groove + .001. If you use #9 onionskin and your grooves are .004" deep that will have you starting with a bore diameter bullet and patching up to groove dimensions
If your bullet is swagged or cast to proper diameter you can avoid sizing altogether. I have never sized a patched bullet. If one is inclined to size conventional GG bullets for this purpose I'd suggest doing that on the front end and avoiding sizing after the fact. It serves no purpose.
