First, lead is much easier on a gun than jacketed ammo is- always.
Second, lead bulleted ammo can leave a lot of fouling and lead streaks/deposits in the barrel if the bullet doesn't fit the throats of yuor gun correctly ( the end of the cylinder that the bullet must pass through to reach the bore). If the bullet is soft it can also lead unless it isn't pushed to fast. It's realy just a matter of matching the ammo components to the gun. It may sound complicated, but it really isn't. If you do some reading here in our handloading forum, you'll soon see pics and read info on what to look for. If you do get leading, buy a Lewis Lead Remover from Brownell's.
Your 19 is a .357 magnum, and will take .38 special ammo of any kind with no problem. +P or +P+. Just avoid any jacketed .357 ammo that contains 125 grain bullets as much as possible. 19's have a reputation for not holding up well with that particular loading, and some have had the forcing cone at the rear of the barrel crack from shooting that particular loading. The 158 grain bulleted amo doesn't seem to do an harm, but the 19 was designed to be a LEO gun- shot once in a while with full power ammo, and practiced with regularly with .38 Special ammo.