Greek mythology inspired girl group 9MUSES released their first full-length album on October 14, 2013, making their comeback performance with the title track "GUN" on M!COUNTDOWN just days before. 

2013 was busy for the group’s nine members with “GUN” becoming the group’s third comeback that year and fifth collaboration with the music producing team Sweetune. The western inspired song kept up momentum built from the group’s previous two releases “Dolls” and “Wild." The constant comebacks also helped them push through member lineup changes and disquieting revelations from the documentary The Nine Muses of Star Empire released that same year. 

Matching the song’s 21st Century take on the 1900s western style, the music video focuses on the glamorously styled 9MUSES at a gas station in the middle of a desert. The girls become reincarnations of Daisy Duke donning red and white stripes, plaid patterns, and short shorts as they wash cars and dance at the station. As a muscular man in a sleeveless shirt rides into the pit stop on a motorcycle, the members can’t help but notice and launch into song, calling for the man to not act coy but instead to be straight up about his feelings. As the music video goes on, we’re treated to close ups of the girls more modernly dressed in flashy rhinestone jewelry, jean bodices, and body contouring dresses. 

9MUSES gave their first performance of the song on M!COUNTDOWN, using the opportunity to show off the member’s vocal skills with an ad-lib intro featuring guitar riffs and brass instruments. The more simplistic stage design paired with the girls' black skinny jeans and dark colored crop tops allowed the choreography to show off the members’ model heights and long limbs. The performance was hypnotic and graceful, with formations mimicking the arms of a clock and four members using chairs to pose.

Promotions for “GUN” ran for about a month until the second week of November, but that didn’t mark a break for the ever hardworking members. On December 3, 2013, they made their fourth comeback of the year with the digital single “Glue,” which also became the last song with members Lee Sem, Eunji, and Sera. Although “GUN” didn’t score the girls their first music show win, the song became their highest charting since debut, peaking at No. 16 on the Gaon Digital SongChart. They were also extended their first invitation to a year end music show, the SBS Gayo Daejun. 9MUSES wrapped up an action-packed year with their final performance on December 29, 2013 alongside their brother group ZE:A.