Who is the father of modern day firearm safety? 

Jeff Cooper 

(Lt. Colonel John Dean "Jeff" Cooper)

 

Who invented what we know as the shotgun?

Daniel Myron Lefever 

American—Daniel Myron Lefever— is credited with having invented the first hammerless shotgun in 1878. A gunmaker by profession. His design for a new shotgun featured a cocking lever on the side of the breech, the first of its kind. The gunsmith patented the hammerless shotgun in 1880, and even improved upon the design in the three years that followed, by internalizing the cocking mechanism to function only when the breech was closed.

 

First rule of firearm safety?

Always keep firearm pointed in a safe direction