Slow fire with careful aim you should group better than 5-6" at 15 feet. Point shoot at self-defense speed... well... that is precisely what you want - 5-6" groups at 15 feet. Sounds like you are doing fine!
Illegitimati non carborundum: Don't let the bastards grind you down
Carborundi non illegitimatum: Don't let the grind make a bastard of you