I don't paint or powder-coat bullets, but I have done some paper-patching. Best results came in 9.3 x 62 Mauser, 30-06, and 8 x 57 Mauser. 30/30 WCF, 38/55, and 45/70.......not so much. My belief--the successful calibers/rifles have gently-sloped leades/rifling origins; the less-successful calibers all have abrupt leade angles. That is called a CLUE at my old job site. Pure lead bullets at 2000 FPS, no gas checks, and accuracy close to 1.0 MOA.
Get (from Wolfe Publications) Paul Matthews' book The Paper Jacket. It is a wealth of information on the subject.
Cores, per caliber, pure lead--
30-06/ Lyman #301618, gifted by a member at the old site. 2 wraps of wet 9# bond paper;
8 x 75/ Lee .316" x 200 grain spitzer, custom mould for my fat-body. 2 wraps of 9# bond paper;
9.3 x 62/ Lyman #358430 195 grain RN, 2 wraps of 9# bond paper.