They came over the Appalachians by the tens of thousands. They were clergymen and farmers, con men and fugitives, gamblers, prostitutes and speculators. In the early years of the 19th century, the Wild West meant the Mississippi and Ohio river valleys. For a young man with ambition, luck and not too many scruples, it was a kind of paradise. Conspicuous even in this flamboyant company was a teenager from Connecticut named Sam Colt. He was, to put it bluntly, a vagabond who had failed as a machinist and a sailor. But in the anonymity and freedom provided by the West, he presented himself as Dr. S. Coult of New York, London and Calcutta. His supposed area of specialty was the administration of nitrous oxide (laughing gas) for medical purposes. For a fee, he would demonstrate its uses. Colt was, as we might put it today, dealing drugs under a false identity.

When he died three decades later, Samuel Colt was one of the most famous men in America and also one of the wealthiest. His legendary revolvers could be found everywhere from the dustiest cabin on the Great Plains to the gun collections of the Russian czar and the sultan of the Ottoman Empire. His Patent Arms Manufacturing Company operated the largest privately owned factory in the world. (The buildings still tower over the Connecticut River in Hartford.) The story of how Colt raised himself from frontier huckster to great American industrialist is the subject of Jim Rasenberger’s lively and balanced new book, “Revolver: Sam Colt and the Six-Shooter That Changed America.” Rasenberger’s narrative is, to a surprising degree, the story of America in the first half of the 19th century. It overflows with relentless ambition, energy, entrepreneurship, ingenuity and wealth, and with deceit, fraud, jingoism and murder.

When Colt was born, in 1814, firearms were primitive instruments. The operator would pour a measure of powder down the barrel, drop a projectile on top, then ram in a piece of wadding to hold everything in place. When the trigger was pulled, some kind of flint or match would send a spark into the near end of the barrel, causing an explosion that would send the bullet out the other end. That was the theory. About a dozen things could go wrong, and often they did. Even when everything worked as intended, accuracy and range were atrocious. A Revolutionary War veteran noted, “A soldier must be very unfortunate indeed who shall be wounded by a common musket at 150 (yards).” Beyond 200 yards, he added, “you may just as well fire at the moon.” When it came to military uses, the great weakness of these firearms was the time they took to reload. Soldiers sometimes carried cartridges, which were powder and ball pre-wrapped in wadding, ready to be rammed down the barrel. But even in these optimal conditions, only an expert could fire three times in a minute.

To solve that problem, Colt drew on his restless Yankee ingenuity to develop a single barrel with a revolving cylinder holding several cartridges. The action of cocking the hammer would turn the cylinder and bring the next chamber into alignment with the barrel. Depending on the number of bores cut into the cylinder, a soldier could take five to seven shots in quick succession. The trick was that the alignment had to be flawless. If the cylinder and barrel didn’t line up, the weapon might explode in the user’s hands. It took Colt many iterations to perfect the mechanism. Contemporary advances in ammunition worked to his advantage. By the middle of the century, Colt had worked out the first reliable, mass-produced “repeating firearm,” the pistol version of which remains essentially unchanged today.

Curiously, the invention didn’t sell at first. It seems few people, even in the military, saw a reason for so much firepower. Or perhaps the design was simply too unusual. Colt teetered on bankruptcy. But then, as Rasenberger nicely puts it, “the universe, having conspired against him for so long, began to reorient itself in his favor.”

Financial salvation came in the person of Capt.Samuel Walker of the Texas Rangers. Walker had encountered early versions of the Colt revolver during the Seminole War. Now, in 1847, he was fighting in the Mexican-American War, and he believed that Colt’s revolver, with a few improvements, would be a valuable weapon for his troops. He traveled east to meet Colt in person, and together they developed the Colt Walker handgun. The Rangers and soon the U.S. government began to buy Colt’s firearms by the thousands. The Walker and its later iterations were so ubiquitous on the Western frontier that “colt” became the generic word for any revolver. Colt the man became an industrial tycoon. For all the unhelpful mythology surrounding guns in America, it remains true that the availability of reliable, inexpensive firearms preserved a degree of individual security and independence in the American West. “God created men,” a Western adage says. “But Sam Colt made them equal.”

Yet Colt’s status as a leading industrialist is inseparable from America’s penchant for violence. His fortune was made by this nation’s genocidal treatment of the native population and its imperialistic war on Mexico. His company’s fortunes, even today, rise and fall with American militarism and our obsession with personal firearms. In a grim concluding passage, Rasenberger notes that the 2012 Sandy Hook massacre was carried out with an AR-15-style rifle, a weapon developed and marketed by the company Colt founded, headquartered less than 50 miles away from Newtown, Conn., in Colt’s home of Hartford.