Now numbering at 24 films, with the 25th due in 2020, the Bond saga has used the gun barrel as a crucial part of the 007 formula, only recently playing with audience expectations during the recent Daniel Craig soft reboots. But while the gun barrel has not changed a great deal visually, one element that has evolved constantly is the music, often used by the composer to put an immediate stylistic stamp on the score and to let the audience know exactly what they're in for.

Interestingly, the first gun barrel—in 1962's "Dr. No"—begins not with music but with a curious clockwork or music box effect, almost winding Bond up as he walks into view before letting him rip. As the blood flows down the screen and the "eye" shakes, the familiar midsection of the James Bond theme—written by Monty Norman and arranged by John Barry—explodes, instantly identifying to the audience that they are in for one hell of a ride, especially as in this case the theme continues over the majority of the subsequent title sequence.

By the time "From Russia With Love" came around in 1963, Barry had a firm solo grasp on Bond. The resulting gun barrel opened not with sound effects but with the mighty crash fans are used to, those two three-note clusters sounding like screaming bullets. As Bond strides in he's accompanied by the vamp section of the theme, the main riff of the theme kicking in just before 007 "kills" the viewer. Barry refined this for "Goldfinger" in 1964 and "Thunderball" in 1965, giving the brass more prominence for the intro section, and with the latter film timing the death transition perfectly—this time the riff hits right as Sean Connery shoots at the screen, perhaps appropriately given that this was the actor's first performance in the sequence (the previous three featured stuntman Bob Simmons).

Barry's cues were wholly representative of the music he was writing for the series at the time: dangerous and seductive, the pure essence of cool. Connery's Bond was the same, a man who you would happily let romance you knowing you were unlikely to survive even the most fleeting of relationships, and Barry's gun barrels personified that to a tee. By the time "On Her Majesty's Secret Service" came around in 1969, Bob Moog's Moog synthesizer had hit the music world with a bang, and as such Barry chose to utilize it to introduce George Lazenby. While the cue begins in the traditional way, the vamp is introduced over a credit for Albert R. Broccoli and Harry Saltzman, meaning that when Bond appears he's scored by the main riff on Moog, which gives the cue a different mood that certainly represented Barry's groundbreaking score, considered by many to be the franchise's best.