I shoot so much that there are large callouses on the inside edge of my trigger finger and the knuckle of my middle finger where it hits the trigger guard. I have to shave them off occassionally and rub Burt's Bees salve in to them so they don't crack open. That's from the Glock. There's another on the first knuckle of my strong hand where it rubs the ambi-safey on my 1911 even though I've rounded the edges. I believe I spend an inappropriate amount of time shooting.
Many guys use adhesive tape on the problem spots too.