Years ago I was plinking at dirt clods about 100 yards away with a 9 mm pistol. The load was with the Sierra 90 JHC. It was late in the afternoon with the sun at my back and every time I shot I it looked looked like I was shooting tracers...really cool.
I thought I was imagining things when I first saw it but I've seen it a couple of times since but as mentioned above, the conditions have to be just right with the sun hitting a shiney bullet base from behind.
