Nguyen Tan Dung is a Vietnamese defense website and posted about this graduated reflex sight that the Vietnamese Military Technical Academy has come up with to be paired with the 40x46mm low-velocity M79 single shot/ stand alone grenade launcher. Although the Vietnamese post was published in the summer of 2015, the innovation displayed here is too strong to be ignored and not shared. This article mentions that components of the sight are produced and assembled in Vietnam. It looks very similar to one of Hartman’s reflex sight designs and knowing that IWI and the Vietnamese government have a very close industrial relationship, I wouldn’t put it too far out that this is the case. The article wrote that although the sight is engineered for the M79 copy currently in use by Vietnamese troops, plans are being made to adjust it to the locally produced MGL copy of the Milknor design when that comes into service.
Now, I am basing the following observations on conjecture. Without a physical lever to move the sight up and down, initially, it would look like the sight couldn’t account for the trajectory of the 40x46mm low-velocity rounds, as is evidenced by the short ocular window. However, upon closer inspection of the sight, it appears that it has a tilting stadia line inside of it, that automatically tilts with the angle of the weapon, possibly due to an internal gyroscope or similar device. This is similar to how the Hartman sight can turn on or off based on the position of the weapon. Ranges are imprinted along the vertical axis, and as a grenadier moves the launcher up or down, the stadia lines move with it, thus allowing the correct amount of angle with the launcher to be used and the grenade fired.
Bear in mind, this isn’t a range finder, nor does it automatically calculate the necessary tilt for an accurate HE solution. Once a grenadier finds out the range to his target, he then aligns the correct stadia distance in the sight to the target and fires the grenade.
It appears that this project didn’t go anywhere, or was successful because I can’t find anything past 2015 about it on the Internet, in Vietnamese or English (unless our Vietnamese readers can chime in with some research?). Which is really a shame because if correct, this technology doesn’t quite exist in this simplicity within a number of modern militaries in Europe or the United States.