Very Weird Question about Speed of Sound
I'm still pretty new here so take it easy on me, guys :) This happened to me about 10 years ago and it bothers the crap out of me that I've never figured out what it was.
Long story short: a bullet (Piney Mountain 22lr tracer) leaves my suppressed rifle barrel pointed almost straight up. Before anyone yells, I was in a wilderness area in VERY remote WV and it had been raining for days.
Anyway when the bullet left the suppressor, it was as quiet as a cat fart. However about a second later as the tracer was very high in the sky, I heard the sonic crack. I was already at a pretty high elevation, it was a humid night I think about 60 degrees temp.
What the heck could possibly cause that??? Even if the air pressure dropped to allow a supersonic crack, wouldn't the bullet have slowed also meaning it would still stay below supersonic?
Does it being a tracer have anything to do with it? Because the other subsonic rounds I fired that night didn't do the same thing. Only the tracers.
Someone that's smarter than me, please give me some kind of clue here. Its driving me nuts.