Hi all,

Can I ask your opinions on the possibility of varmint (or any other bullets for that matter) vaporizing mid flight?

I saw a V-max literally disintegrate with a grey vapour trail, could the bullet vaporise?
Is this a common occurrence?
Has anyone else witnessed this before?

Any help is appreciated!

Deerifle: Bruce Potts wrote an interesting article in April's Shooting Sports mag regarding various .17 centerfire cartridges. I think he had a 15 grain berger vaporise whilst doing some testing. Let me know if you want a copy of the article and I'll dig it out.

You pose a very interesting question.

The bullet itself driven very fast with tight rifling will fly apart. I have seen this reported many times. The vapor trail you saw could be that.

An interesting aside; back in the 50's the Air Force came up with the X-15, it was a rocket plane. I think it could reach speeds of about 4,000 mph. One of the problems with the plane was heating of the airframe. A couple of instances the skin had burned through, they were using nickle-steel at certain turbulence points. I wonder what the aerodynamic heating of a bullet is coupled with the heat transferred during the ride down the bore?

Some bullets will turn to smoke clouds based on to much speed with to tight a twist. VarmintAl's website has an excellent example designed for all the engineers out there.

In my own experience a 37gr calhoon will become the worlds smallest shotgun at about 3700fps when fired from my 1x7 twist .223AI. I started zeroing a scope at 25yards and all I found on the target was a pattern about 7" in diameter. Moving the target closer the bullet showing signs of failure at 10 yards. I believe the noslers and Vmax have a thicker base that will minimize the problem while still retaining their explosiveness.

It's not thermal failure and they don't 'vaporize'. They do suffer material failure due to centrifugal forces that exceed jacket strength. Hornet bullets will routinely fail around 3600 fps with a 12-14" twist.

Digital Dan hit it on the head. Loaded some Sierra 40 grain Hornets in my .22-250 trying for that magical 4000 fps mark. You could see the bullets come apart about 75 yards out.

[ 05-24-2003, 17:40: Message edited by: crowrifle ]

I've had the odd bullet appear to vaporize in my .22-250Rem. I don't think that's what it is really. I think the jacket comes apart in flight and gives the appearance of vaporizng. I'm not absolutely sure, but it seems that way. This is especially true with thin jacketed bullets. Best wishes.

Cal - Montreal

I can also tell you from personal experience that the 107 gr MK will come apart at 3650fps from a 1-8 twist barrel. My 6mm-284 wears a 30" LIja heavy barrel and I have seen it. I backd her down to 3550 and she shoots 1/2 moa....whoo-aahhh.

Years ago I was loading for a .220 Swift, and the 52 grain Speer hollowpoints would sometimes come apart in flight and do a gray streak. Even the bullets that made it to the target showed a spray of lead around the bullet hole. It looked like the lead core was liquid and the jacket ruptured about 40 yards or so down range. My son really liked to shoot those.

jim dodd

Actually, it's structural damage, not centrifugal force, that destroys bullets in flight. The damage occurs when trying to force too thin a jacket into too tight a twist at too high a speed.

Centrifugal force contributes a little, but the jacket is already damaged when the bullet emerges from the muzzle, and aerodynamic factors are the major culprit from then on.

One thing no one mentioned; a rough bore can contribute greaty to the demise of a thin jacketed bullet. Normally it takes excessive speed to dust bullets but it will happen at a much lower velocity if the bore is rough.
Conversely, a particularely smooth (hand lapped) bore will allow you to shoot frangible bullets at a much higher velocity before the jackets disintegrate.
Moly can also play a role here.
VH

The Speer 223 50 grain TNT bullets will fail in flight if loaded much over 3400 FPS, or if fired out of a Ruger Mini 14 with a fast twist. All that will hit the 100 yard target is bullet dust.

I don't know why it happens, but it does. My 26 inch TCR83 barrel has been known to make the gray streak mentioned above with lighter bullets and max charges of H414 in 22-250.

regards,
Graycg

[ 05-26-2003, 15:33: Message edited by: graycg ]

[QUOTE]Originally posted by British:
[QB]Deerifle: Bruce Potts wrote an interesting article in April's Shooting Sports mag regarding various .17 centerfire cartridges. I think he had a 15 grain berger vaporise whilst doing some testing.

Here are the facts:

Shooting Sports April '03, page 64 shows a black and white photograph of his aluminium target stand with the caption

"The bullet splash (top left) was a 15-grain pill vaporising as it hit the aluminium target stand."

What is shown is a roughly triangular patch of discoloration radiating from a point on the vertical edge of what looks to be an ally plate. At the narrowest point, the patch is of fairly uniform colour which becomes patchy as the distance from poi increases, reducing to a number of thin radial streaks.


If the bullet really did "vaporise" ie change from solid to gas, the marks would have to have been caused either by deposition as the gas cooled and returned to solid state, or by the heat generated to change a solid metal to a gas. OTOH, it could simply be that the bullet exploded on impact into a number of very fine particles and that the colouration is the deposition of those particles.

The article is in reference to .17 Rem. I have skim-read the article for you and can report that, despite references to 15gn projectiles and mv >4000fps there are absolutely no references to projectiles not reaching their intended destination in any condition other than in one piece.

1st= bullets come apart from to many RPM. 2nd=The lead smear on the targer is because hot gas gets past the bullet while the bullet is still in the barrel. The friction of the air on the bullet tip as it goes to the targer (100 yds) keeps the lead in a liquid state.

It is very much a thermal condition. Heat is directly imposed on the bullet due to frictional and pressure forces while the bullet is in transit down the barrel. The consistency of the lead within the copper jacket is nearly a molten state. That is the whole basis behind why bullet technology progressed to the point where jacketing the soft lead allow was necessary to gain higher velocites. Pressure and continued friction from air molecules outside of the barrel sustain the molten state for a relatively short distance out of the muzzle. That is why if the jacket is compromised due to too high of a rate of twist in relation to the veolcity, you get the famed puff of blue/gray smoke.

Model7AWR

I've been of the belief that the bullet failure is due to the extremely high rotational spin. I read awhile back of Roy Weatherby's experimenting for the U.S. Gov't to achieve very high velocity (I think over 4000fps) with a 30 cal. bullet. If I remember correctly he did this with the 30-378 and an "undesclosed" amount of powder but with a smooth bore rifle. I think he chose a smooth bore to keep the bullet from flying apart as he wasn't really as interested in the accuracy as he was the speed.

Something no one else has mentioned, is that it is possible to "vapor trail" without any bullet problems. Here in the humid South, early morning shooting often produces vapor trails. They are more noticeable shooting 200-300 yds, usually with the quick-stepping rounds. I guess they are close kin to the contrails we see in the sky, created by the turbulence from a plane's wing tips. But, do watch your target for the telltale lead smearing about 1/2 inch around your bullet holes. That will tell you that you're gettin' close to havin' trouble.......Bug.

Bug is correct. Given the right combination of temperature and humidity I have seen relatively low velocity "silhouette" rounds leave vapor trails. The vapor trail in itself is no cause for concern. What does or does not happen at the target is what tells the tale.

There are some excellent replies here and it is obvious that most of use have witnessed this phenomena in one form or another.
One thing that is certain is that bullets can, and obviously do fail in flight, from the replies there are a few possible reasons why this could happen.

But....

What about vaporizing?

Could the surface temperature of the bullet in flight so to speak reach 327.5 �C melting point lead?

I found an atmospheric temperature calculator on line but the results were in Rad's.
The program suggested that a bullet 0.01" long with a velocity of 3000 fps would heat up to 518.659 "fR" which I guess would be 518.659 Rad's.

Does anyone know how to compare these two temperatures?

Thanks for all your input in to this!

Sorry, that was a bullet 0.01' long not 0.01"

As mentioned above, the .22-250 will easily smoke many light bullets designed for the Hornet.

I once got the bright idea of trying Sierra .264/87 grain HPs in my 6.5-300Wby. The Powley calculator put my starting load (87 grains H870) at about 4,100 fps, twist is 1:9. Shot prone, the grass and dirt 10 yards out front looked like it was raked with a .410. I don't believe the bullets ever began to spin and just skipped along the grooves, since it took about a week to get the copper out from two shots. In this case, my guess would be structural damage.

It's structural damage first, completed by spin. Amused myself years ago watching it:

Had an AR-18 and some 30-round mags. Loaded some hot book-loads with .224" light varmint bullets ('cause I had lots). At the range, I let off a full-auto burst at a 100-yard target and was astonished to see a lot of grey puffs scattered in the air between me and the backstop, with a few hits tossing dust on the backstop. Kinda neat.

So, tried it some more and got the same results. A few rounds gave a grey trail climaxed by a nifty little grey cloud hanging in midair.

I figured out that the thin jackets were being cut by the rifling but gained a "normal" ballistic spin anyway. However, once cut, the jackets did not hold together. When they finally flew apart, the unsupported alloy lead cores disintegrated from rotational stresses.

Paladin

Early in my shooting and reloading carrer, long, long ago, Hornady made a bullet designated .224 SX (for Super Explosive). These were designed for .222 Rem. Veloicities. I tried them in my then new Mod. 700 ADL .22-250 at around 3,600 fps. They never got to the target. I watched as someone else shot and could see blue puffs of smoke about 10 or 20 yards out. If they didn't vaporize then they blew apart. What's the difference?
Rich Elliott

I have had it happen to some bullets over 4000 fps
but I have pushed the Nosler 40 and 50 grain ballistic tips well over 4000 and have not had one blow up as of yet.

Deerifle,

Depends on the bullet. At one time I was testing a new bullet by Sisk for the .222. Thought I'd give it a try in a .22-250. Almost drove me crazy. I couldn't hit the target. Then I realized the bullets were coming apart about 10' from the muzzle. Have a great weekend.

I have had commercial Winchester .223 45gr JHP High Velocity bullets come apart on me. Winchester does not recommend them in barrels with a twist faster than 1/9. They run 3,600fps according to Winchester.

I found this after I shot them in a rifle with a 1/8 twist, and wondered why the 3rd round obliterated my group and left a "shotgun blast" on the paper. Happened several times.