Vapor trails and varmint rifles


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MLC
December 31, 2002, 01:42 AM
I have read about high velocity rounds leaving a contrail type streak in the air and wondered what type of conditions were required for this phenomena? Muzzle velocity, humidity, temperate and lighting are important I'm sure. Has anyone seen this first hand? I am working up some 4000fps loads in my 6mm and remembered reading about his somewhere.

added:
I recall now reading in a gun rag about 10 years ago an article on 4K+ velocites. They had pictures showing a contrail from muzzle to target, also there were orange/red streaks from the excessive velocity loads.

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Gordon
December 31, 2002, 01:50 AM
Oh yes it is real; if you use "blitz" or other super frangible bullets out of their velocity range. I have seen it from 110grain .357 bullets over 3000fps. If you approach 4000fps with bullets advertised as blowing up at Mach 2 you will get it. A rough bore or dirty barrel makes it happen sooner. Damp weather doesnt help. Phenomena is unpredictable and aint no tracer. I forgot that fast twist make 55 grain "blitz" bullets do it in full throttle .223 loads-sometimes.:uhoh:

3 gun
December 31, 2002, 02:02 AM
Last time I saw this happen was with my 22 Mag. More weather and light, than round dependent.

telewinz
December 31, 2002, 08:16 AM
I had it happen one time when I was shooting an AR15. The bullets looked just like white tracers, really neat.

Fatelvis
December 31, 2002, 06:25 PM
I saw it about 10 yrs ago. A guy was shooting a 22 Cheetah and its velocity was in the 4K range, he said. I didnt doubt it. Never saw it since!

wyote
January 1, 2003, 08:10 AM
If you are shooting long range (300 to 700 yards) it's not uncommon at all to see the vapor trail. Just set up behind the shooter with a spotting scope or at least 10X bino's on tripods. This can also be done with a video camera set on the hightest power.

The bullet doesn't have to be going 4000 fps to see the vapor trail. I've seen vapor trails on everything from 45 colt to 338 win mag. The 7 stw and the 22-243 are 2 of the best to watch.

Steve Smith
January 1, 2003, 08:08 PM
Wyote got it, at least I think so. I commonly see the trail of the bullet (every shot in fact) when I am at a match watching through my scope and a shooter is firing. I dunno if it's some "vapor trail" or what, but I can definitely see where each bullet is going, and where it impacts. Get right over and right behind the shooter.

Gewehr98
January 1, 2003, 08:30 PM
My spotter could see EVERY round of my 6.5-06 heading towards the targets. He calmly gave me bullet path status as the rounds hit or missed their little steel targets. He was set up to my left, fairly close to the barrel of the rifle. Worked quite well, as a matter of fact. Sometimes, he'd laugh and tell me it was gonna be a hit, before the round smacked the steel. Good spotters are so hard to find these days. ;)

jsalcedo
January 2, 2003, 02:20 PM
I used to shoot a lot of 38 special target loads I assume the velocity was somewhere around 600 FPSand they had next to no recoil or smoke.

When the sun was setting off to my left I could watch each round zip to the target as the sun glinted off the lead round.

I may be wrong but it looked like 2/10th of a second to go 25 yards

HSMITH
January 2, 2003, 03:20 PM
I think there are two different phenomena being discussed here. One is the wake of the bullet seen through optics like a match shooter spotting. I have seen this and it can be seen on EVERY shot if the light is good. Quite normal.

The second one I have seen on a couple different occasions, and that is a contrail that is visible to the naked eye. You see the path of the bullet without optics as a white streak, that may or may not start and stop as the bullet flies. I have seen it where the contrail starts at the muzzle and fades away within 200 yards, but I have also seen it start at 50 yards or so and then go a very long ways out. In all instances that I can recollect somewhat clearly the humidity was VERY high and light was strong. I have only seen this occur with 50 BMG and 7.62x51, with 50 being at least 75% of it.

My SWAG at what it is: As the air is compresed by the supersonic bullet passing the moisture in the air is forming water droplets, and we see the light reflected off of the water droplets. I have seen this on low level aircraft as well when very close to or beyond the sound barrier.

Any other guesses as to what it is?

Larry Ashcraft
January 2, 2003, 04:26 PM
HSmith; you are right, there are two phenonema being discussed here. I've seen bullets fired from a .45 auto when the sun was behind me. If you watch the target being fired at at the moment of firing, you can actually see the bullet.

I have seen the vapor trails also, but in my case a friend had loaded Hornady SX's for a Mini 14. They left a neat white trail. The tight 1:7 twist of the Mini was ripping the thin jackets right off and the lead would disintegrate in the air. (it says right on the box of bullets "not for use in Ruger Mini 14))

Redlg155
January 2, 2003, 04:58 PM
Never got to see one on a varmint rifle.

Now If you stand behind a 155 mm howitzer using "green bag" propellant you can actually see the round leaving the tube and follow it for a fraction of a second.

Good Shooting
RED

MLC
January 2, 2003, 05:27 PM
Now If you stand behind a 155 mm howitzer using "green bag" propellant you can actually see the round leaving the tube and follow it for a fraction of a second.
Let me know next time you go to the range, I'd love to see that!;)

hps1
January 2, 2003, 06:35 PM
Have never seen the contrail phenomenon but coaches use the bullet trace to keep their shooters in the black on team
matches regularly, and as gewehr98 said, can tell whether the shot will be on target or not by where the arc of the shot breaks.

Darndest thing I have seen was at Camp Bullis coaching a 300 yd team match (shooter was firing either 30-06 or
.308). The sun was just right so that each shot fired by my shooter appeared as if you had run a shiny copper wire
from muzzle to target. IIRC, the sun was fairly low from about 10 o’clock.

Regards,
hps

HSMITH
January 2, 2003, 07:39 PM
The indoor range I go to has a couple lanes with lighting just right, you can see 38 specials and 45 acp pretty easily. I have not had much luck seeing the faster bullets.

Southla1
January 2, 2003, 08:35 PM
In as much shooting as I have done I have never seen a vapor trail. We used to watch 45 and 38 rounds all the time both with the naked eye and a spotting scope during pistol matches.

One time when the sun was just right there were 3 of us that saw the bullet from a 25-06 go down range. It was as hps1 described. It looked like a wire going from the rifle to the target.

PS: I hate to admit this because it ages me but that was in the days BEFORE Remington made the 25-06 a "non-wildcat".

RugerOldArmy
June 6, 2006, 09:55 PM
FWIW, I seem to remember reading that military spotters (sniper teams) use this, having, as I remember, optics slightly out of focus to see it better.

rero360
June 6, 2006, 10:41 PM
Now If you stand behind a 155 mm howitzer using "green bag" propellant you can actually see the round leaving the tube and follow it for a fraction of a second.

I've also seen this with the MK19, its pretty cool, have also seen .45s and .40s go down range as well, haven't had a chance to watch a round go down range using the trail.

rbmcmjr
June 6, 2006, 11:29 PM
Naval 5"/54 exhibits that as well, given enough humidity.

Rick

Medusa
June 7, 2006, 06:32 AM
It is supposed to do with humidity, when the air is oversaturated with water vapour then the passing bullet might cause the condensation of the excess water, thus creating the vapour trail, similar to vapour chamber detector where passing particles are visualised like that.

hksw
June 7, 2006, 12:32 PM
To actually see a vapor trail, the relative humidity should be somewhat high and the temperature shuld be close to the dew point.

However, you really don't need a vapor trail to see rounds go down range. More imoprtantly is, IMO, lighting and the position and angle you are watching from. On a clear non-humid day, I was spotting for a co-worker one time during a varmint hunt at another co-worker's farm. He was zeroing in his Colt HBAR 6601 and I was spotting with 7X50 binoculars. I was standing about 5:00 back and above. I could clearly see dark bullet images going down range every time he fired. Unfortunately, he was aiming at a target about 10 feet from a pile of irrigation pipes and the rounds were impacting into the pipes. It was a costly hunt.

If you watch some of the military shows on satellite, they'll have specials on various organizations and show footage of rounds from sniper rifles going down range on clear days. Your able to see on film the wake of the sound waves in the air from the sonic boom being produced by the bullets as they head down range.

hank327
June 8, 2006, 12:19 AM
I've watched 8" and 155mm howitzer rounds fly downrange while standing behind them. As a member of an 81mm mortar platoon, I often watched the mortar rounds in flight. I just stood some distance behind the tube and watched a point some distance in front of the barrel. It was easy to pick up the round in flight and watch it until it seemingly reached the apogee (sp?) of it's flight and tip over to begin its descent towards the target.

de
October 27, 2006, 03:12 PM
The only vapor trails I have ever seen were from own doing. I once necksized a bunch of 2506 brass, and loaded them without cleaning the lube out of the case necks. I was in a hurry. Using a million candle power spotlights on coyotes the lube left a vapor trail that looked like a white vaper trail behind a plane. My hunting buddies thought it was the neatest thing they had ever seen and tried it themselves. I have no idea how a bullet that is not engine driven could produce enough heat to form a vapor trail regardless of how fast it is driven. Being trained as a sniper I learned that gases from the powder will follow a bullet out of a rifle for 2 to 4 feet but no further. This was proven to me by an instructer shooting glass. At 2 1/2 feet from the muzzle the bullet strikes the glass, the gases chasing it up-end the bullet causing it to tumble and not strike the target behind the glass or hit at a different point of impact. Move 5 or more feet away, and the gas has lost its effect on the base of the bullet causing the bullet (308 in this case) to penetrate the glass and hit very close to its intended point of impact if not exactly on it. In short, after firing thousands or rounds of pistol and rifle from 38 special lubed target loads to 220 swift and other rounds. I don't believe bullets cause comtrails or vapor trails on their own regardless of the atmospheric conditions. They have no heat source more than a few feet beyond the barrel. I too have watched bullets travel down range with the sun to my back, but this is not a vapor trail, just good lighting.

WayneConrad
October 27, 2006, 03:36 PM
It doesn't take a heat source to make a vapor trail.

Check out the photos here (http://cellar.org/showthread.php?t=11113).

Post #12 has an explanation of how airplane wings can cause vapor trails. I can't tell you if that explanation works for bullets.

Lambo119
October 27, 2006, 03:43 PM
I have had sun glint off of rounds before from pistol to rifle. Even had a batch of "bad" bullets for a .17 remy that came apart at about 150 yards when shot. Looked like sparkley metalic confetti in the sunlight and took me about eight shots before I figured it out. Lucky I didnt have one come apart in the barrel.

Only one time did I ever see a con trail behind a bullet. My buddy and I were out shooting my .50 BMG at about 500 yards and noticed it on the 2nd round fired. This was pretty cool so we shot seven rounds or so and kept trading the gun back and forth so the other could see it better. It did not last long about fifteen minutes and then we could not get it to do it again. We both agreed that it was weather related. It was a morning that the temp was rising quickly pulling the moisture out of the gound and making a very slight haze.

30Cal
October 27, 2006, 03:44 PM
FWIW, I seem to remember reading that military spotters (sniper teams) use this, having, as I remember, optics slightly out of focus to see it better.

If you focus the scope on the target, the wake will only be in focus for a split second. If you focus about midway to the target, it's in focus longer and it'll stand out better against the target/background.

Ty

Bridger
October 27, 2006, 06:06 PM
I saw the vapor trail last week. A guy was shooting a .22-250 at the 50 yard line, and it was like a smoky white laser to the target every shot. At first I thought he was shooting tracers. It was pretty cool, I should have gotten some video or pictures, darn hindsight!

I've also seen the sun glinting off of .45 and 12 gauge slugs before, pretty cool.

Dave R
October 27, 2006, 06:18 PM
A few of the free video clips at www.dogbegone.com show either vapor trails, or just the air wake, of the rounds being fired. If you've never seen it before, you can see it there.

BrainOnSigs
October 27, 2006, 07:07 PM
I have seen bullets distrupt heat waves and make them swirl...very cool.

Groundhog
January 10, 2007, 10:51 PM
I have seen vapor trails using my 243 while hunting groundhogs. Only seems to happen when conditions are jjjuuuuussstttt right. We are in eastern Virginia, and humidity is quite high a lot of the time. Especially late in the afternoon when the sun has been out all day, but the clouds are rolling over, but not making it cloudy, that phenonemnon seems to happen. Most of the ones I have seen start somewhat out from the muzzle, and I do not rmember the trail ever getting to what I was shooting at, but it may have. I will take better notice this coming year and follow up and let ya'll know. I seem to remember that it happens in the spring and later in the fall, but not during, lets say July or August, but I will take notes.
Groundhog.......
:)

SaMx
January 11, 2007, 12:21 AM
I think the vapor trail is caused by high humidity. When the bullet flies through the air, it creates low pressure in the void behind it. That's where most of the drag that slows the bullet down. If it is pretty humid then the moisture in the air will condense, and leave a trail. I don't think you need especially fast bullets, as long as it is supersonic and very humid it should leave a vapor trail.

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