He went to school in Oxford, Texas, (pretty much a ghost town now, about eighty miles west of Austin) and liked to say that he was the only Oxford educated Ranger. He worked in his father's smithy as a kid, and was a teenage horse wrangler. He joined Ranger Company C in 1906, and -- in his early 20s -- was something of an Earp or a Hickok in cleaning up Texas border towns.
The chief of the Texas Department of Corrections commissioned Hamer to put together a task force and bring down the gang. (His instructions were pithy: "Put 'em on the spot, know you're right -- and shoot everybody in sight.") Hamer was promised a king-sized portion of the reward money that various banks had posted, and was told he could have anything he wanted from the Barrow gang's huge arsenal, when taken.
Bonnie Parker and Clyde Barrow were driving a stolen 1934 Ford V8 down a lonesome country road near Gibsland, Louisiana when they were ambushed by Hamer's crew, pretty much like you saw in the movie. (That's them, Hamer front row left.) The fusillade was ear splitting, and upwards of 167 steel jacketed bullets tore into the car. Locals thought they were hearing dynamiting by area road workers.
Hamer himself was carrying a distinctive rifle, a customized .35 caliber Remington Model 8 fitted with a 15-round magazine. In his shoulder holster was a Colt .38 Super semi-automatic. (Frank liked .38 Super because it goes through a bullet-proof vest better than a .45.)
Frank Hamer retired in 1949, died in 1955, and is buried in Austin. During the span of his life, he was shot 17 times, left for dead four times, and is credited with killing between 53 and 70 men.
Just for the record: That depiction of Frank Hamer in the movie Bonnie and Clyde was BS. Shameless, unadulterated Hollywood crap. He's shown as being captured by them at one point, humiliated and then released, and brings about their deaths purely for personal revenge. You can bet your Colt .38 Super it didn't happen that way. Bonnie Parker and Clyde Barrow couldn't kidnap Frank Hamer on their best day. The Hamer family sued Warner Brothers-7 Arts for defamation of character and got an undisclosed out-of-court settlement in 1971.
Postscript: The banks reneged on the promised reward money. Frank Hamer and his posse ended up splitting just over $200. He did take all the guns home, though...