“Colt revolvers have always been the blue chips of gun collecting,” says Greg Martin, president of Greg Martin Auctions. “The romance, the craftsmanship, the history. Sam Colt the man, the promoter, the first American industrialist. All wrapped together it [really makes] an American story.”

An impressive chapter in that story will soon be up for grabs. On September 18 in Dallas, Martin will auction what he believes is the most significant group of Colt revolvers put together in the past 50 years. The Al Cali Collection features nearly 30 Colts made from 1836 to 1865 during the percussion era, including one of the finest known examples of Sam Colt’s very first pistol model, the Texas Paterson.

It was the Paterson—embraced by the Texas Rangers in the early days of the Lone Star republic—that served as the foundation of Sam Colt’s rise as America’s preeminent gun maker. Though his first manufacturing business failed in 1842, the Colt revolver had made its mark. The pistols that followed—the Walker, the Navy, the Dragoon and other models featured in the Cali Collection—were improvements on the original design Sam Colt patented in 1836.

The $6 million collection includes workaday pistols like an 1849 Pocket model (more than 300,000 manufactured) to intricate one-of-a-kind art pieces and presentation models given to important dignitaries, business associates and friends of the Colt family. “The collection is not big in number, but the guns in it are really world class—the ultimate of their kind,” Martin says. Here’s a look at the top 10 guns in this remarkable trove.