Erkki, the colour and how thin the tracers look in the picture match exactly what i saw in real life.
What doesn't match is the length. In reality, they would appear shorter when close to the observer (that is, when leaving the barrel) and almost immediately "shrink" to the size of a dot, just like the ones in the 110 picture.
Of course, the human eye is like a camera shutter too in some respects and if we accept that variation in "eye specs" between most people is less than the variation between human eye and camera, then we should all perceive motion in a more or less similar manner.
In this case, the type of shell being fired will also have a small effect on how we see it. For example, a faster shell will produce the impression of a longer streak.
That being said, i think the guns in your video are Oerlikon 30mm or 35mm guns. They are different from the ones i fired but maybe not perceived as too different by the human eye, as it was a 20mm cannon itself and their muzzle velocities might be in the same speed range.
For a better explanation of how those rheinmetalls i fired looked in real life, it was like having the length, width and "reduction to a dot at a distance" effect of the machine gun rounds in the videos posted in the first page of the thread, but with the speed and colour of the tracers in your video. I hope this makes sense
