From GrabCAD developer John Fall thank you for your work in this great community!!!

https://grabcad.com/library/m79-grenade-launcher-request-1

File updated 20/11/2022
The M79 was a result of the US Army's Project Niblick, an attempt to increase firepower for the infantryman by having an explosive projectile more accurate with further range than rifle grenades, but more portable than a mortar. Project Niblick created the 40 x 46 mm grenade, but was unable to create a satisfactory launcher for it that could fire more than a single shot.
May not be perfect but some of the drawing are difficult to read .