"I've heard that some people patch with teflon tape - I would think that would be much thinner - maybe I'll just go measure it."
Hi Cat Whisperer... Good luck with the telfon, can't say if it will work for you or not as all my experiments with telfon, excepting muzzleloaders, has been a total flop.
It appears to me the "real thing", whatever that may be, ends up being a good "stout" paper of light weight. A very hard item to find nowadays. The old story of two wraps around the bullet does seem to be best when you end up with + / - .001 to .0015 oversize. At least for me. I am going to patch up a .338 / 220gr. cast from pure lead, using plain computer printing paper, ending up at approximately .356, with hopes it will bump up to at least .357, and maybe .358.
Don't have a clue what to expect with the first attempt, but if it don't work I was comtemptlating adding a couple wraps of real tight telfon over the regular paper I've been using (9lb.@ .002)
My "learnings" tell me that more than two wraps of anything is not good but I guess I need to see for myself the difference.
Let us know how your bullet turns out. I have a Shilen bbl. 1-14 twist on my Rifle and it does very well with the 280gr. 358009. I have also got the RCBS 358-200 and the Saeco 247gr. The 200 grain seems to do worse that the heavier weights, but that could be a matter of load development, as others report good results with the same twist.
Russ