Exactly what causes the black ring around bullet holes in the target? Does anyone know?

I don't mean to be a "SA" but how about a "hot bullet"

I always thought it was the hot gas fouling at the base of the bullet rubbing off as the bullet passed through the paper.

It always seemed to be more evident around the larger part of the hole (base of the bullet) and much less in the center (when you flatten the holes back).

quote:

Originally posted by Bill Mc:
I don't mean to be a "SA" but how about a "hot bullet"

Hi SA :

Yes, I've thought it might be the high rpm and velocity actually "burning" (charring) the paper too. But let's wait and see what other answers we get here.

quote:

Originally posted by Flippy:
I always thought it was the hot gas fouling at the base of the bullet rubbing off as the bullet passed through the paper.

It always seemed to be more evident around the larger part of the hole (base of the bullet) and much less in the center (when you flatten the holes back).

Good point.

I think it is carbon fouling, gathered from between the lands by the bullet as it passes over the lands. Did somebody already offer this?

quote:

Originally posted by rootbeer:
I think it is carbon fouling, gathered from between the lands by the bullet as it passes over the lands. Did somebody already offer this?

Not exactly, but your idea would seem to explain the lack of "black" at the center of the hole.

I think you are on to something...

I vote carbon or barrel steel rubbed off the bullet. I doubt there is enough contact time to burn the paper if the bullet were at the melting point.

Pass a torch across a piece of paper as quickly as you can and let us know. The would control for the carbon if the flame is clean and smoke-free.

I bet the paper is not burnt.

quote:

Originally posted by Papa Capp:
I vote carbon or barrel steel rubbed off the bullet. I doubt there is enough contact time to burn the paper if the bullet were at the melting point.

Pass a torch across a piece of paper as quickly as you can and let us know. The would control for the carbon if the flame is clean and smoke-free.

I bet the paper is not burnt.

Something about Fahrenheit 451?

What this thread is revealing so far is that so far no one here (at least) knows the answer for sure.

That's information by itself.

I've emailed one of our resident forum experts fo his input...let's see...we WILL get to the answer...right?

Answer: YES WE WILL!!!

If need be, spectrographic analysis could shed some light.

quote:

Originally posted by sonofagun:
If need be, spectrographic analysis could shed some light.

Shed some light, good one!

Along with shooting in the IBS 200-300 yd. National championships this past weekend, I worked the target detail. Having read this post earlier I looked very closely at the targets. All the holes had the "black ring" regardless of being shot with Moly, Danzac, or naked bullets. I was suprized to see the "black ring" on the Homosote and Celotex backers as well. There must be plenty of carbon on those bullets.

Eddie, we used to have a shooter by the name of Eric Klementich that coated his bullets with a white substance, I think he said boron. His bullet holes looked like a paper puncher made them. No black ring. Butch

Well, "resident expert" couldn't shed any light on this either...

surely I'd think it might have been researched at sometime.

I'm with rootbeer.

Lacking a fancy budget for high dollar testing equipment and lacking common sense and good judgement--I went downstairs and pulled a few targets out of the drawer. I folded a few tight groups in half and inserted them into my mouth for a taste. You get a very clear and clean carboard / construction paper taste. After you get things good and slobbery you get a transfer of powdery / gritty material that has a distinct "bite" which reminds me of licking your finger after shooting firecrackers.
OK smart guys---go analyze that!!!!

Further "taste tests". Don't ask don't tell.
After tasting the black rings I tried the different components--brass=nothing,bullets=nothing,raw powder flake,ball,stick all=nothing.
I scraped residue out of a fired case=I got the same powdery texture virtually no taste. I would have to say this is part of the answer. The "bite" that is encountered in the powdery material seems to be coming from the primer. If you scrape a primer pocket you get the same bite or taste. So my vote goes for a combination or interaction of the primer/powder after ignition.
No for another question???? Is this embedding into the bullet? Why does it not blow off at 3000 fps or greater? That is some good sticky stuff holding it on if its just powder residue.

Hey Rootbeer--Now that you started this. Why is the carbon not being completely/totally blown out of the barrel when we fire? Why the devil is there anything left in your barrel at the kind of pressures and forces that the inside of the barrel sees? What is causing this material to stick to the inside of the barrel?

Here is a little bit of info that might contribute something to the discussion, although it is not Benchrest related. A while back I acquired an old commercial Army&Navy 303 British Enfield sporter with open "Express Sights". The bore had been heavily used and abused over the years, and looked like a dirty, rough sewer pipe with very worn rifling. My first trip to the range produced keyholes at 25 yards (see below). I did not want to replace the barrel and ruin any nostalgic or collector value, so I decided to see if I obtain any semblence of accuracy with the original barrel.

Slugging the bore revealed that the barrel had a groove diameter near the muzzle of .317", near the mid point it was .316", and near the chamber it was .318. Since all these measurements were well over normal 303 British I decided to try something dramatic. As luck would have it, I also work with some old J bore 8x57 Mauser sporters, and had several types of .318 and .317 diameter bullets on hand.

I removed as many layers of powder and jacket fouling as possible, substituted some .317 and .318 bullets in my handloads, and headed back to the range. As can be seen in the second photo, the first few shots from a clean barrel produce not only a black ring, but a "comet tail" as well (this was at 35 to 40 yards, although the rifle will now do as well at 50 to 60 yards). The tail disappears after a few shots, but if I then fire another group with the .318 bullets, the tail reappears for a few shots. I concluded that the larger diameter bullets cause more carbon fouling to be released from the grooves, and as I put more rounds through the barrel the "tail" has become less evident.

One other interesting effect showed up during shooting as well. Round nosed bullets tended to cut cleaner holes with much less black around the hole than spitzers regardless of how clean the barrel was. Additionally, the amount of paper removed in the center of the hole was always greater with the more blunt bullets as would be expected by anyone who has ever used wadcutters in handgun shooting.

Jim

Interesting stuff. Your keyholed shot would indicate that this "black material" is on the entire bullet, not just on the front or rear portion of the bullet as I had previously thought.
I have an 1884 trapdoor 45-70 that had a filthy barrel as you described. I took steel wool and wound it on a bronze brush with plenty of Kroil Oil. Cut off a Dewey rod and chucked it up in the drill. That bore is shiny now---and shoots very well now also.

one-holer:

Heat... and pressure. Apply enough heat and pressure to just about anything and you'll see some interesting changes in properties of materials and willingness of people to see things your way.

What is really interesting is that nobody actually knows for certain what this stuff is.

I vote for one-holers taste test results, primer residue.

Oh BTW, Rootbeer, I like the 87 billion dollar quote. I thank God everyday that JK was NOT elected president.

I have an idea. If someone could shoot lead buckshot at a paper target & then shoot copperplated buckshot. Would this not tell us whether the lead of the bullet "stains" the paper. The copper plated and lead are covered by the wad. So I'm hoping that this will shield it from the powder residue. Smoke it over and see if you think that this will work.

quote:

I have an idea. If someone could shoot lead buckshot at a paper target & then shoot copperplated buckshot. Would this not tell us whether the lead of the bullet "stains" the paper. The copper plated and lead are covered by the wad. So I'm hoping that this will shield it from the powder residue. Smoke it over and see if you think that this will work.

That is a good experiment!

I Think it is a dirty bullet like many here do.

The lead smear or tail in mbogo375 photos are caused by gas blow by in the barrel. The lead tip of the bullet becomes liquid because of the gas blow by in the loose barrel. When the bullet hits the air , the air friction keeps the lead soft and melting on the way to the target, 100 yards in my case. The NRA confirmed this many years ago. I owned such a rifle in 243win., the barrel was shot out or the groove dia. was larger than the bullet, or undersize bullets, i would also keyhole some bullets, not all and did not shoot well till after at least 10 shots fouled the barrel. Then most groups would stay under 1"@100yds

I think this guy is onto something. So as not to belabour the issue, I had a 22-250 with a ER Shaw barrel. It was so rough, after 20 rounds I could guarantee that at least one of the five shot group keyholed. Additionally, they were also accompanied by a grey "misting" around the keyholes. I think the bullets were being torn apart by the rough bore and the lead was melting.

quote:

Originally posted by 243winxb:
The lead smear or tail in mbogo375 photos are caused by gas blow by in the barrel. The lead tip of the bullet becomes liquid because of the gas blow by in the loose barrel. When the bullet hits the air , the air friction keeps the lead soft and melting on the way to the target, 100 yards in my case. The NRA confirmed this many years ago. I owned such a rifle in 243win., the barrel was shot out or the groove dia. was larger than the bullet, or undersize bullets, i would also keyhole some bullets, not all and did not shoot well till after at least 10 shots fouled the barrel. Then most groups would stay under 1"@100yds

But, and its a big but, I have seen these "rings" with FMJ and X-bullets also. No lead tip to "melt."

It is difficult to believe the lead tip actually is molten while the bullet is in flight, otherwise centripetal force would “fling†the molten lead from the front cavity and the air rushing over the tip would “blow†the molten lead away.

And what about cast bullets? Using that theory they would be completely distorted from being “melted.â€

I have recovered many different types of bullets from various mediums and several looked much as they did right out of the box (except for the rifling grooves).

My vote was and still is gas fouling on the surface of the bullet.

quote:

Originally posted by 243winxb:
The lead smear or tail in mbogo375 photos are caused by gas blow by in the barrel. The lead tip of the bullet becomes liquid because of the gas blow by in the loose barrel. When the bullet hits the air , the air friction keeps the lead soft and melting on the way to the target, 100 yards in my case. The NRA confirmed this many years ago. I owned such a rifle in 243win., the barrel was shot out or the groove dia. was larger than the bullet, or undersize bullets, i would also keyhole some bullets, not all and did not shoot well till after at least 10 shots fouled the barrel. Then most groups would stay under 1"@100yds

But if this was the case, the "tail" would be there all the time. In this particular instance, I can confirm that it was only present after the barrel had been cleaned/brushed. The more I worked with the barrel, the less "tail" I got following cleaning.

I still think that it was due to powder fouling that was loosened by the brushing/cleaning. I have worked with a good many vintage rifles over the years, and the British rifles that were used with cordite powder seem much more likely to show this pattern. In many cases they have NUMEROUS layers of powder and jacket fouling built up over the years, and it can be a long process to get it all out with conventional cleaning procedures.

Once the built up fouling is gone, the "tail" disappears as long as the barrel is cleaned frequently, and new fouling is kept down. The "tail" looks blacker (more like carbon) than the tail you get from molten lead. I had a 220 Swift that had a tendency to vaporize 46 grain hollow points that were designed for the 22 Hornet/218 Bee velocity range, and the marks on the target (when there were any ) from the lead were more of a grayish color.

This may not explain all instances of a black ring around the bullet hole, but it certainly is an interesting phenomenon .

Jim

What is most interesting is that no one has one single definitive answer for this phenomenon.

As Mr. Spock would say, "fascinating..."

I believe it is due to the graphite used to coat powder granules so that it meters consistently.

quote:

Originally posted by Strawboss:
I believe it is due to the graphite used to coat powder granules so that it meters consistently.

I thought of that initially, but the "primer pocket taste test" would eliminate most of that I would think.

I know the pressure rises after ignition to the point where equal force is in all points of the case/primer area, so what ever is in the case is in all parts of the case. But the primer pocket seems to have more crust in it then other parts of a fired case. Also some powders do not seem to have near as much graphite on them as others.

I have seen the same black ring on holes made with black powder bullets, and black powder has no graphite coating that I know of.

I think the high pressure exerted laterally against the target material is causing a low temperature carbonization ring. Note that there is less "dark matter" in the center of the hole than at the edge. The center area of displaced paper has less lateral pressure than than the outer area.
To test this a target frame that can hold several targets at a 1/2" or 1" seperation. if the ring is on the first target but is less pronounced as it passes through more targets then it is combustion products. If the rings are consistant throughout then the phenomena is local.

Take note that in photos of mbogo375, the 228 gr bullets dia. is .318" a longer heavy bullet, more area to seal the bore. The bullet with the "tail" is 170 gr with a dia. of .317" less dia. less sealing area because of less bearing surface.We have 2 things here, a tail and a black round ring. The black round ring can be bore fowling or even coming from a black target backer as bullet passes through it and springs back,this ring is common to see. I did not know where the "tail" came from till someone sent a photo to the NRA asking where the "tail" came from. As in my last post that is what the person at the NRA said.I go with what they said because of other things that can happen to a bullet in flight. Has anyone ever shot a 22 center fire where the bullet has broken up in midair and never reached the target? Strange things happen, we may never know what caused the "tail".

I vote that the bullet friction against the paper is charring the surface lightly...at bullet velocity the pressure between the surfaces should be large enough to cause instant high heat!

It can't be powder residue pickup because I get them uniformly on the first shot from a bright, shiny clean barrel.

I had this problem some years ago with my .308Win. It was dirty around the outer edges of the bullet hole and also the case necks were filthy. I always assumed it was the Winchester 760 powder I was using (don't know this for certain). Anyway I switched to another powder, and the problem went away. Best wishes.

Cal - Montreal

quote:

Originally posted by Swamp_Fox:
I think the high pressure exerted laterally against the target material is causing a low temperature carbonization ring. Note that there is less "dark matter" in the center of the hole than at the edge. The center area of displaced paper has less lateral pressure than than the outer area.
To test this a target frame that can hold several targets at a 1/2" or 1" seperation. if the ring is on the first target but is less pronounced as it passes through more targets then it is combustion products. If the rings are consistant throughout then the phenomena is local.

This makes the most sense so far, at least to me.

Maybe I will set up a test and see.

If you rub bullets on paper, it does leave a faint black/gray mark...

Go for it!

An amazing thread. Hasn't this ever been addressed by other shooters at some time? I mean like in any NRA pubs or popular gun rags?
Heck, if I had his number, I'd call up Jim Carmichael and ask him about this!

This carbon ring can be really confusing.
On the left of picture 1 you find a group with nice carbon rings while the lower group has less carbon around the holes.
Picture 2 shows 5 groups with nearly no carbon rings (when you enlarge the picture you'll find that most of the dark is shade) and the four tags on the lower right (pasted to the targer)are absolutely clean (in spite of being 1 foot from the muzzle).
6mm PPC with Euber FB bullets and 1.65 grams REL 7.
All loads are the same (where I find that RELODER 7 is the cleanest powder I ever used).
The explanation for the difference in carbon ring is mostly due to paper quality (brittle target paper in pic.2 has no rings, and writing paper in pic.1 is elastic like toilet paper - and has the same effect).

http://www.hunt101.com/showphoto.php?photo=339674
and
http://www.hunt101.com/showphoto.php?photo=339677

quote:

What is most interesting is that no one has one single definitive answer for this phenomenon.

Gnat guts. Usually you can't see 'em the air unless the light is just right.

quote:

Originally posted by Clem:
I guess you need a geeky Engineer sticking his yap into the fray.

A supersonic bullet will have a shock wave and an area of compression directly in front of the meplate.
My theory is that the meplate and ogive never actually make contact with the paper. The area of compression in front of the bullet initiates the hole and only the shank of the bullet contacts the paper. That is why you have a black ring and no discoloration of the center portion of the paper.

As for the ring I believe it is from a very brief contact with heat - above the point of combustion of the paper but so brief that it does not ignite. An SR71 Blackbird travels close to the speed of your bullets....

I will give you the shock wave theory for no marks at the “point of impact.â€
After watching video of the car that broke the speed of sound, taken from a chase plane flying overhead, that shock wave was VERY evident.

As for heat being the culprit. An SR71 does (did) move at a speed near average bullet speed, however it did so for an eon compared to the flight of a bullet. Plenty of time for the leading edges to heat up, so much heat the planes could not be worked on for a couple of hours after landing.

I don’t believe a bullet has enough time of flight to heat up to anywhere near that temperature, especially a handgun bullet moving at 600-700 fps (cowboy action loads).

There is plenty friction and heat, but it would have to reach a temperature hot enough to get the paper to nearly 451 degrees F in about a millisecond. Take a propane torch and wave it in front of a piece of target paper. That flame has to be on one spot a lot longer than the bullet is as it passes through to discolor it.
I just don't buy it.