Ignoramus6213 wrote:
I was at a gun range today with a friend, shooting a 9mm hand gun.

When he was shooting, I was standing behind him, watching. After a few
shots, I realized that I may have seen a glimpse of the bullets as
they flew downrange.

I watched some more, and it did seem this way, although it was hard to
see them and the barrel flash did not clarify things.

I am wondering, if, perhaps, it is known that flying bullets of that
sort of size and speed can be actually seen.

i
Low velocity subsonic pistol bullets can be seen from behind . I've seen
muzzleloader balls/bullets myself - these are larger diameter and slower
than most pistol bullets however . A guy with keen eyesight and fast
reflexes might very well be able to see 9mm slugs in flight if conditions
are right . Neither my eyes nor my reflexes are capable of it ...
--
Snag
Learning keeps
you young !