Mk 20 Mod 0 grenade launcher

{{Infobox weapon

| name = Mk 20 Mod 0

| image = File:USN_1146266.jpg

| image_size = 300

| caption = Mk 20 Mod 0 Grenade Launcher (upper left) on a US Navy Strike Assault Boat

| origin = United States

| type = Automatic grenade launcher

| is_ranged = YES

| is_bladed =

| is_explosive =

| is_artillery =

| is_vehicle =

| is_missile =

| is_UK =

| service =

| used_by = US Navy
Karen National Union

| wars = Vietnam War
Internal conflict in Myanmar

| designer =

| design_date =

| manufacturer = NOS Louisville

| unit_cost =

| production_date =

| number =

| variants =

| spec_label =

| weight = 26 pounds

| length = 27 inches

| part_length = 12 inches

| cartridge = 40x46mm SR

| cartridge_weight =

| caliber = 40mm

| barrels =

| action = Blow-forward

| rate = Semi-Automatic
250-275 RPM Full Automatic

| velocity = 250 feet per second

| range = 350m

| max_range = 400m

| feed = 24 round belt

| sights = Iron

}}{{One source

| date = April 2021

}}

The Mk 20 Mod 0 was a 40mm automatic grenade launcher manufactured by NOS Louisville which was used by the US Navy during the Vietnam War. The Mk 20 was eventually replaced by the Mk 19 Mod 3.