We found that a .7CC or 1.0CC of APP under the ball will be most sufficient for the 62 Police/Pocket Navy. The 15 gr's of what you speak will blow the caps off the nipples.
You will be way over power for the 62. Unless of course, if you do not want to run the little piece fast, or for competition.
We spent a Morning at the range using various load, nipple and Hammer spring combinations.
Our findings were; the .7CC Lee dipper of APP, slix-shot nipples, stock Hammer spring would maintain performance, shooting the five chambers as fast as we could. Four out of five caps would still be on the nipples when the run was complete.
Just passing along some experience for what its worth. Yours may vary from the above, however we are quite pleased with the results we obtained.