Calibre 50 is a Mexican conjunto of norteño music created in the city of Mazatlán, Sinaloa, in the year of 2010.The group is also considered to be "Norteño-Banda", as it features a Tuba to play the bass notes, instead of an electrical bass or a Tololoche, which are more commonly used in Norteño music. 　　Before founding Calibre 50, Edén Muñoz had been the accordionist and vocalist in a group called "Colmillo Norteño". With Muñoz, the group scored the hit songs "Sueño guajiro" and "Hotel El Cid" in 2009, among others. Nevertheless, conflicts with the other members of the group led Muñoz to quit Colmillo Norteño in December 2009, and he founded his own group in 2010, recruiting Armando Ramos as guitarist, Augusto Guido as drummer and Martín López as Tuba player. The name of this new group was "Puro Colmillo Norteño", and they recorded their first album, "Renovar o morir", under that name, as well as their first single ("El infiernito"). However, the original Colmillo Norteño sued them for the name, and after a legal dispute Muñoz' group was forced to change their name later in 2010. They chose the name by which they are known nowadays: Calibre 50. The name of the group comes from the comparison "with an element that will symbolize the strength and impact that the project has on the lives of the members, as well as those who like the regional Mexican genre." 　　Calibre 50 first achieved notoriety for their controversial songs and corridos. Their first nationwide hit was "El tierno se fue" ("The nice guy is gone") in 2011, a song written by Lalo Ayala which contains many innuendos and describes a sexual act in detail. In later years they turned to release romantic songs as singles, however their albums still consist mostly of corridos and party songs. 　　In January 2014, drummer Augusto Guido left the conjunto to work on his own group, "Los de Sinaloa"; he was replaced by Erick García. Two months later, Tuba player Martín López also left the conjunto to work on another project, "La Iniciativa". He was subsequently replaced by Alejandro Gaxiola. 　　Calibre 50 made history when the group became the first Regional Mexican band to perform on the Conan show. 　　Calibre 50 made their Houston Rodeo debut on March 11, 2018 to a sold out Houston crowd. 　　On April 26, 2018, Calibre 50, along with Colombian singer J Balvin, received an award from Pandora Radio for being the first artists to surpass a billion of streams on that platform.