I would slug the barrel and see what the groove-to-groove diameter is. If the barrel is oversized, using more powder may not address the leading issue, especially if the bullet diameter is undersized for the barrel and/or the bullet alloy too hard for the velocity/pressures used.
Another member had leading issues with a new SR9 pistol using harder alloy bullets and I sent an assortment of MBC lead bullets sized .356" and .357" (BHN 18) and while the leading decreased, it did not entirely eliminate the problem as the barrel was oversized (I believe .357"+). I even suggested squishing the bullet down with a vise to size the bullets to .358" to see if that would help but leading continued.
Many suggested the member simply use larger sized bullets than groove diameter but the problem is larger .358" sized bullets would not always chamber in all factory barrels as chamber dimensions vary.
I ultimately suggested the member contact Ruger to see if a barrel swap was an option and after some fuss with customer service/technical department, in the end the member received a replacement barrel with .355"-.356" groove diameter and leading problem went away using typical .356" sized bullets.
BTW, all of my KKM/Lone Wolf barrels' groove diameters range .355"-.356" and I do not get leading with various powders and bullets (MBC 18 BHN, Dardas 16 BHN, ZCast 14-16 BHN) and even with lighter charges.
FYI, Glen Fryxell has an excellent free ebook on issues related to leading (definition/detection/location/prevention/removal) and chapter 7 is a wealth of information that should be referenced when working with lead bullets -
http://www.lasc.us/Fryxell_Book_Chapter_7_Leading.htm