During the ARC troopers' operation to save Ki-Adi-Mundi, they utilized the under-barrel grenade launcher. The under-barrel grenade launcher, alternatively called an over-under, functioned as a miniature rocket/grenade launcher for special forces. By way of an underbarrel attachment, this weapon could be affixed to a modified DC-15A blaster rifle, DC-17m Interchangeable Weapon System, WESTAR-M5 blaster rifle or an E-15A blaster rifle, allowing for the firing of diverse explosive projectiles.
When Advanced Recon Commandos rescued Jedi Master Ki-Adi-Mundi and other Jedi from General Grievous on Hypori, they employed these weapons. The grenade barrage, while failing to inflict substantial damage on the exceptionally nimble Separatist general, served to distract the cyborg as he evaded the explosions.
Mace Windu also made brief use of this weapon while on his assignment to Haruun Kal.
On missions to Chashima (in 29 ABY) and Vandor-3 (in 44 ABY), Voort saBinring utilized a blaster rifle equipped with an integrated under-barrel grenade launcher.
The Model MGL-1, the Viper & the Viper 2, and the HH-4 are all examples of under-barrel grenade launchers.