I remember hearing this when watching Mel Gibson in "The Patriot" but I remember that his prayer was incomplete.
Here it is in its entirety:
The Gunfighter’s Prayer
Lord, make me fast and accurate. Let my aim be true and my hand faster than those who would seek to destroy me. Grant me victory over my foes and those that wish to harm to me and mine. Let not my last thought be “If only I had my gun”; and Lord if today is truly the day that You call me home, let me die in a pile of brass.
H/T to Gun Nuts Media