CARRONADE: We were with Inshore Fire Support Division 93; my ship, Flagship, was the U.S.S. Carronade (IFS-1). She was built for the Korean War, decommissioned and recommissioned for Vietnam. I sailed with her as a plankowner in 1965 through 1968. She was built from the keel up as a rocket firing ship. The LSMRs were old LSMs (Landing Ship Medium ) that later received the "R" designation (Rocket). 

The U.S.S. Carronade had 8, mk5 Rocket Launchers and could launch them with pinpoint accuracy ... 5,000 in just a few moments!; one, 5'38, duel-purpose gun; and two, twin, forty-milimeter, "Pom Pom" guns. Also, lots of 50 and 30 caliber machine guns. 
Source: Vietnam Veteran's Terminology and Slang

Augmented by Carronade (IFS 1) and St. Francis River (LSMR 525) in April 1966 and Clarion River (LSMR 409) and White River (LSMR 536) the following month, the Naval Gunfire Support Unit increased its bombardment of the enemy. This assistance was especially welcome in I Corps during the latter half of the year, when main force NVA units attacked south through the DMZ. Indeed, from mid-1966 on, the naval command concentrated the majority of the gunfire support ships off I Corps where combat was heaviest and the geography most favorable for inshore bombardment. In one action on 13 September, Stormes (DD 780) guns killed over 200 enemy troops in three hours of firing. By November almost 40,000 rounds were expended each month by the surface group off South Vietnam. Throughout the year the force killed 3,000 of the enemy and damaged or destroyed 35,000 structures.

Source: The Years of Combat, 1965-1968