Vapor trail and Bullet trace:
Vapor Trail: Now there is something that I have heard only mentioned breifly but have never seen. I was told that if the conditions are correct and you are a spotter you can actually see the vapor trail of the bullet as it goes down range. One unusual thing I did see is while hunting and sitting off the the side and watching a friend fire a 2506, I was actually able to see reflective glints of light with the sun angled in just right. But vapor trails – can anyone eloborate on this phenomenon. Thanks.
In a state of confusion in the merry old land of , Ohio USA – Thursday, November 19, 1998 at 00:33:19 (EST)
Al – What you are refering to is what we call “trace”. It can be seen in almost all conditions with a good scope and is what the observer watches to call his second round if the first is a miss. Use a 15 – 20 power scope and get just above and almost on line with the shooter. At two hundred look right in the middle of the target. Trace will appear at that point. As you go further back the higher the trace will appear and as you adjust for wind the more up wind the trace will appear before it curves towards the target. At 600 the trace will appear about 4 foot above the target and disappear about 18 inches above impact (on a normal day), by the time you are back at 800 to 1000 the trace will appear about 10 – 12 feet above the target and disappear about 4 foot aboe impact. Focus your scope about 2/3 of the way to the target to get best read. Then play with the focus until it comes in. You can video tape trace as well to wow your friends. On a day that the light is behind you, the bullet can be seen with the sun glinting off of it. Buy an Optolyth and trace is next to impossible not to see.
Fayetteville, NC USA – Thursday, November 19, 1998 at 01:08:13 (EST)
Just want to expand a little on vapor trails and traces. A bullet trace is a disturbance of air pressure which causes light to be refracted differently. This is similar to what you see in a shadowgraph or schlieren photography.
A vapor trail is a different and rarely seen. I have only observed vapor trails only twice and that was when shooting a .220 Swift. I used to seriously hunt varmints back in the ’70s, and had the Harts rechamber a new 40-XB .22/250 for the .220 Swift. Humidity, temperature and dark background all have to be favorable for this phenomenon to take place and be seen. The vapor trail is white in color and comes from the change in air pressure at the back of a bullet. Just like the temporary trails that jet fighter wing tips produce when doing maneuvers. This trail hangs in the air for about a second and then vanishes. We observed it both on the 100 yd range and when shooting a groundhog across a bean field. Unlike a trace one does not have to be directly behind the shooter to see it.
Have you ever heard of the .22 Blue Streak cartridge? This was a wildcat that master gunsmith Al Marciante came up with in the early 1940s. It was named Blue Streak because it was observed to sometimes cause a streak from muzzle to target. The name stuck.
That is about all I know on the subject.
USA – Friday, November 20, 1998 at 01:31:23 (EST)