I'd look no further than 3.3gr to 3.6gr of bullseye and a 158gr bullet.
Also look at coated bullets in the future sized to .358".
I've posted these groups before. 6-shot groups @ 50ft from my 686. They are only @ 50ft because that's the typical distance I use them at. I either shoot 50ft nra bullseye or we do a spinoff of bowlingpins. We use 12ga shotgun shells @ 50ft instead of bowling pins @ 25ft.
A 200 round range session with those bullseye 3.3gr loads pictured above. The 686 doesn't need cleaned until the 700+ round mark.
There's no leading with those coated bullets. It takes a wet patch with nothing more than hoppe's #9 to clean the bbl.