Some of us on this forum have been reloading / handloading for many years. For me, that is for almost three decades. The first thing I would like to say is buy a stinking manual. Buy the most current Lyman's manual and read the beginning chapters that deal with the best practices to follow while reloading. Be careful, be patient, be very careful. I often suggest that a handloader have at least three reloading manuals, because not all of the manuals say the same thing.
You should also start a reloading journal. My father has been reloading for more than four decades and can go to his journals and point to detailed information about any and all loads he has ever made. We have handloaded ammunition from the 70's, 80's, 90's, and 2000's and packaged with those rounds is a tag that lists all the information about that load along with a Ref# that can be found in the journals. You don't have to be that organized, but it helps.
As for a plinking powder, I would suggest Unique. You can find data for Unique for almost everything handgun related from 32 Auto to 480 Ruger Magnum.
•Most versatile powder made
•Good in all popular pistol calibers
•Great for light 10 gauge, 12, 16, 20 and 28 gauge loads.
Unique is a great plinker powder.
Originally Posted by Wolf Spyder
"Only large manly men and very dangerous mythical creatures can handle the raw power of the 10mm"