Unusual phenomenon from a high speed bullet

[Old teacher]

I was recently at the range shooting a number of my rifles, but primarily my .257 STW, one of my favorite guns built on a Remington action with a 26 inch barrel plus a Vais brake. I was shooting a load that drives an 85 grain bullet at about 3900 ft/sec, and is very accurate. The weather was sunny, temperature about 75 degrees, no wind, about 50 ft above sea level. I shot a couple of groups at 100 yds, and all was normal. I switched to two hundred yards, and that is when things got weird. When the bullet passed through at about the 125 yd mark a perfectly round ball about the size of a basketball made of what I assume was water vapor appeared for just an instant and then disappeared. It was visible long enough to get a good look at it. It happened on every shot, and always at the same distance. It gathered a crowd and I ended up going through a whole box of ammunition because everyone wanted to see it several times. I tried a couple other rifles with slower bullets and could not duplicate whatever that was. We have all seen water vapor come off the wings of jet fighters at high speed turns, and these two phenomenon I assume are caused by the same thing. Has anyone else experienced this, and/or does anyone have an explanation of how this occurs? It has never happened again with the same gun and load, thank goodness. I should have charged admission.

 

[Varminator 911]

Did the bullets reach the target? Because it sounds like the bullet was blowing apart. I've seen this shooting light fragile bullets way too fast in a 220 Swift. Those seemed to vaporize at about 20-30 yards. Poof and they were gone.

 

[Broz]

Did the bullets reach the target? Because it sounds like the bullet was blowing apart. I've seen this shooting light fragile bullets way too fast in a 220 Swift. Those seemed to vaporize at about 20-30 yards. Poof and they were gone.

Exactly, I had a swift loaded up once and the 50 gr bullets would not make it to a 200 yard target. A visible grey puff could be seen as the bullet vaporized.

Jeff

 

[royinidaho]

I did that a bunch when the 17 Rem was new.

I heavily suspect I experienced it the other day w/a 300 Berger Gen 1. The only thing in the video was a poof. Bullet didn't reach the target @ 980.

 

[Old teacher]

That was my first thought...that the bullet was disintegrating. But that usually happen closer in. What ever was going on not only did not disintegrate the bullet, it also did not affect accuracy. All the groups were under 1.5 MOA, most were about half of that, which is what this rifle usually shoots. I walked up to the target expecting to see no holes or holes all over the place, but there were just nice tight groups.

 

[RTK]

Atmospheric conditions must have been perfect in some strange way to cause that. Either that or you were hitting the invisible aliens at your range

 

[Old teacher]

Yeah,LOL, eliminating those range aliens has always been a problem for me. They cause flyers, inexplicably large groups, misfires, blown primers (the fact that I was pushing a 50 grain bullet over 4500ft/sec had nothing to do with that)cases that either won't come out or come out in fifteen pieces, destroy perfectly good throats that have had only 4000 rounds through them, and a host of other bothersome problems. I hope I killed 20 of them. I asked a jet pilot who happened to be my neighbor and he said they get the same phenomena with whole airplanes when atmospheric condition are right as RTK mentioned, and airspeed was in sync with those conditions. He said it was nothing you could feel (which semi-explains why I still got good groups), or even see because it was caused BEHIND you and was not something you could see yourself go through. It was usually confirmed by a pilot flying back of the affecting airplane. So, unless someone expert in these sorts of things has something to add, we will leave it behind as an interesting day. It was, I assume, a ball of water vapor caused by the bullet building up pressure in the air to the point where that pressure compressed the water vapor in the very nearby area to the point of being visible for just a flash, and it apparently occurred just behind a very high speed bullet and did not affect it's flight. According to my pilot friend, who was a test pilot for the military and can and has flown everything the military has produced, my incident is somewhat related to the reason that a jet airplane has to have either slanted or very short wings that will guarantee that the aircraft is completely inside of the cone of air pressure built up by the high speed of at least a mach one airplane just before it breaks the sound barrier. I think I got that explanation right, but if not, I am sure someone with experience flying mach one or faster aircraft will correct me. And any correction would be most welcome. Thanks to all who responded. One side note: if you are looking to build a barrel-burning wildcat, the .257 STW is fast, very flat shooting, low recoil, and very, very accurate with a number of loads. Behind my faithful 300 Win mag Sendero, my .257 is my favorite rifle, and I have taken a significant number of deer with it, some it very long ranges.