KF9VH: shooting lead slugs from a new barrel will not firelap it. If you feel you need to lap your pistol barrel, and Veral Smith recommends you do for the best accuracy, then you will need to lap it first before youstart throwing lead downrange.
If your barrel is rough and you start shooting lead bullets before you lap it, all you will get is a lot of lead deposits in your barrel that will need to be removed before you begin the lapping process.
You can properly lap your barrel in about 30-50 rounds using the proper materials and process, which is really a buncha fun.
It would take you thousands of rounds of jacketed slugs to create the same 'controlled wear' that the lapping process imparts to a new barrel.
I would recommend you drop on down to Veral Smith's forum for recommendations and discussion on the firelapping process. It has worked for me for a long time and I recommend it. HTH. Mikey.