if you're not well trained, you might as well leave that heavy lump of steel locked up at home. It won't do you any good anyway.
If you can hit the paper @7 yards, are AWARE of surroundings ( hypervigalent is better
) and they dont "get the drop" on you....then you can reasonably expect to defend yourself with a pistol.
That does not mean you should NOT practice, or train, or learn to draw fast....they do increase your odds.