Ghost rifle / Max McCoy.

A "Pinnacle Books."

"Descended from a long line of ramblers and rogues, Jack Picaro came to America to seek his fortune. But after killing his best friend in a drunken duel, the apprentice gunsmith flees westward, behind children he does not know, Gus and April. As Jack ventures up the Missouri River, he finds an unspoiled land where a man can live free--and also be attacked by an Arikara war party. His rifle stolen in the bloody skirmish, Jack sets out alone to reclaim it. His wild escapade ends in a fight to the death with a legendary Crow warrior named Standing Wolf. So begins a fateful epic search across the last frontiers of the untamed West. From the muddy banks of the Mississippi to the shining peaks of the Rockies, Jack Picaro will leave a trail of clues for an abandoned son, Gus, to find him: a famous gunsmith who will make history with a weapon of his own design--and forged a legend that would be passed down for generations. This is the story of the Ghost rifle."