4barrel,
Yes they are easy to see, and especially if it's really dark. I'm talking about at night without any ambient light anywhere close and without a full moon. That's the best conditions to see them well. It also makes a difference if you are the shooter and if you are shooting at a target or a sandbank for a backstop. Shooting after dark requires some serious preparation since those bullets travel much farther than you can see! But if you are not the shooter and are standing somewhat to the side (not out beyond the line of fire of the shooter, you will have an angle view of the bullet flight and can see the full tracer as it flies through the air. It can be pretty impressive. However, having seen many, many rounds of 40MM shells with tracers fired, the small .38 Special is a tiny light in comparison. You can see the big rounds tracers in daylight, but you are lucky to see the .38 Special then, unless there is a dark background and you are placed where you get the angle view.
I have fired the .38 Special tracers from the training firing line where we trained with the 40MM guns during the daylight as well as during hours of darkness. There was no worry at all about targets down range there. And there was room to stand a good ways down the firing line from the shooter so you got a good view of the tracer's flight path. In that case, the tracer would burn itself out well before the bullet remaining struck anything. The tracer would disappear in the air in mid flight. The 40's fired one tracer in every five rounds. The other four rounds contained High Explosive charges in the projectile. You couldn't see them in the air but knew they were following the tracers. When those HE rounds hit anything, or when their timing fuses set of the HE charge, you could definitely see them explode, in the air or on the target. Never fired a .38 Special tracer round at a solid target that was close enough to see what happened if the tracer was still alive. Pretty sure I wouldn't do so today either!!
I never did hear what the purpose for those military .38 Specials were originally intended to do. Perhaps someone here more informed than I can tell us!