I have rovered bullets trapped in cloth that have melted the fabric onto themselfs. These same bullets show heat discolouration in the rifling engraving and on the surface contacting the grooves in the bore. These bullets were fired at low velocity mostly. The melting was near the base of the bullet. The same thing happens with faster bullets that muzhroom and can be stopped by the rags.

The quetion is; can jacket heating within the bore cause the jacket to come loose from the core when the bullet leaves the muzzle, resulting in an imbalanced bullet and hence affect accuracy?

I always wondered if it melted those plastic ballistic tips and they were all for show.

Good question, I have loaded the wrong bullet too hot before and gotten strange results so from them I would hazard to guess that you are corrrect.
I loaded some 22-250 ammo once in an extremely accurate 788 and the first two shots did not hit the paper, the next keyholed and the next became a small grey cloud of smoke halfway to the target.
i often have wondered about that since then.
For if the jackets were simply too thin then why would the lead disinigrate in the air like that unless it was also molten?
A solid lead core even sans jacket would have still traveled downrange would it not?
So what happens exactly inside a bullet that vaporizes in midair?
My theory has been that the lead melts into a liquid, the riflings score the thin jackettoo deeply, and the centrifigul forces of the spinning bullet cause it all to some apart, and the velocity and rpms cause the lead to simply come apart into a grey cloud of mist.

I personally believe that the tales of bullets melting during their travel from breech to muzzle is caused by one or a combination of the following:

a. Bullshit
b. Old wive's tale
c. War story

I don't know about melting but to much velocity also equal to many RPM's due to rifling pitch.
A bullet not rated for a specific velocity can be ripped apart by centrifugal force. I've seen it happen but only on twist rate higher then 1-9

I doubt that a rifle bullet's jacket/core can melt in any way; the barrel time is VERY short, 1.2/1.6 milliseconds, depending on barrel lenght and bullet velocity.

It's not about melting but rather, expansion of the jacket from frictional heating which as pointed by out wildboar, occurs over a very short time duration so will be very localized, i.e. confined to the jacket at the contact area. This must result in expansion of the jacket if it is thin enough or hot enough and so far, I have seen that it gets plenty hot - hot enough to melt fabric! But this heating is not caused by contact of the hot gases pushing against the base of the bullet. There is not enough time for that! (Not more than just a few degrees anyway).

This is a subject hotly debated on the benchrest forum by bullet makers and other experts. What I got from the debate was that the problem can occur if one is not very careful in the choice of components that go into making bullets especially using what most call out of date techniques.

If the bullet world is much the same as the brass world. barrel world, trigger world, and etc, I would presume that core separation is a lot more likely to occur when using the more cheaply made bullets, especially at high spin/velocity rates.

quote:

Originally posted by 303Guy:
It's not about melting but rather, expansion of the jacket from frictional heating which as pointed by out wildboar, occurs over a very short time duration so will be very localized, i.e. confined to the jacket at the contact area. This must result in expansion of the jacket if it is thin enough or hot enough and so far, I have seen that it gets plenty hot - hot enough to melt fabric! But this heating is not caused by contact of the hot gases pushing against the base of the bullet. There is not enough time for that! (Not more than just a few degrees anyway).

If the jacket expands from the heat in the bore does it expand outward loosening it`s grip, or does it expand inward gripping tighter??

quote:

Originally posted by 303Guy:
...this heating is not caused by contact of the hot gases pushing against the base of the bullet. There is not enough time for that! (Not more than just a few degrees anyway).

Could be due to "Blow By", if there is not enough Pressure to cause the Bullet to completely obturate. Since you are Catching the Bullet in a Box of Rags, I'll go with Blow By as the likely source.

I’ve loaded a 17 Remington to the point that the bullets (25-grain HP) came apart, producing whitish streaks and nothing hits the 100-yard target. I’ve chronographed my 17 Remington test loads up to 4657, the white streak shots were somewhat faster (I don’t know how fast). I know they are very small, thin-skinned bullets but it was interesting.

The barrel timing on the 17 Remington moving at 4600 fps out of a 24 inch tube is only .719 ms. Not much time to gather a lot of heat from barrel friction or blow by.

My question is, what effect does air friction have on bullet heating?

quote:

Originally posted by Ol` Joe:

quote:

Originally posted by 303Guy:
It's not about melting but rather, expansion of the jacket from frictional heating which as pointed by out wildboar, occurs over a very short time duration so will be very localized, i.e. confined to the jacket at the contact area. This must result in expansion of the jacket if it is thin enough or hot enough and so far, I have seen that it gets plenty hot - hot enough to melt fabric! But this heating is not caused by contact of the hot gases pushing against the base of the bullet. There is not enough time for that! (Not more than just a few degrees anyway).

If the jacket expands from the heat in the bore does it expand outward loosening it`s grip, or does it expand inward gripping tighter??

Path of least resistance
A piece of steel shaped like a donut heated will expand out ward ID and od will get larger

quote:

Originally posted by MickinColo:
I’ve loaded a 17 Remington to the point that the bullets (25-grain HP) came apart, producing whitish streaks and nothing hits the 100-yard target. I’ve chronographed my 17 Remington test loads up to 4657, the white streak shots were somewhat faster (I don’t know how fast). I know they are very small, thin-skinned bullets but it was interesting.

The barrel timing on the 17 Remington moving at 4600 fps out of a 24 inch tube is only .719 ms. Not much time to gather a lot of heat from barrel friction or blow by.

My question is, what effect does air friction have on bullet heating?

Mick-

I too have had many .17 Rem bullets come apart when using my "winter" load in warmer times of the year. My standard winter load is a 20 grain Berger bullet at an ave chrnono'd velocity of 4406 fps. In winter that is a sub 0.5 MOA load. In Spring and summer, an average of less than 2 out of each 5 bullets fired even reach the target.



Your question about the affect(s) of air friction on bullet temp I think is a good one. In my opinion, ANY friction which is slowing a moving object creates heat. Truck brakes are a great example.

Whether there is enough air friction to melt a whole bullet core, I do not know, but I suspect there may be enough to AFFECT a bullet...

After all, the whole core does not have to melt...only the surface portion which is in intimate contact with the jacket. Not only that, but the whole bullet length does not have to be melted either to cause imbalance...just a portion of it...then centrifugal (sp?) and other forces may very well throw it wildly out of whack.

The SR 71 blackbird grows 6" in length during flight at mach 3 It's made of titanium and doesn't melt but it is definitely affected by air friction

quote:

Originally posted by kcstott:
The SR 71 blackbird grows 6" in length during flight at mach 3 It's made of titanium and doesn't melt but it is definitely affected by air friction

10-4. It also reportedly turns a dull red from the heat generated shoving the air aside and leaks fuel like crazy until warmth from air friction expands things and seals all the joints.

303guy, not too long ago some 1000 yard competitors were having trouble with bullets shedding thier jackets,6.5-284 rifles with Berger 140 grain VLD's. Berger did some research and found that the long bearing surface coupled with the long barrels and high velocity was heating the core enough to cause the jacket to shed in flight! So Berger came out last year with the 140 grain VLD BT Thick. Refering to the new thicker jacket.Problem solved.

BLOW BY -The hot gas will start to melt a lead nose spitzer type bullet in the barrel. As the bullet travels to the target, the air friction on the lead nose keeps it hot enough to keep sheading lead. Any time the bullet jumps to the rifling the bullet is heated. An example of this is using 55gr bullets in a 243win. When the bore is not sealed before the bullet base leaves the case, extra gas cutting of the barrel and heating of the bullet happens. The white target will have a lead smear on it. This is NOT a round carbon ring.Blow by only happens in well worn barrels. If your rifle will not group till after 10 or more shots are fired, you have a barrel problem. BULLET BLOW UP- This happens with "blitz" type varmint bullets at velocitys above 3700fps in most cases. 22-250, 220swift, 224/6mm Rem Wildcat with fast twist barrels. Carbon fouling in the barrels scores the bullet jacket, the bullet comes apart on the way to the target. CORE STRIPPING- does the lead inside the jacket move or firing? No one knows for sure. Olin has a patent process to keep bullet cores from moving inside the jacket.Olin Patent

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Not much time to gather a lot of heat from barrel friction or blow by.

Barrel friction is not a function of time but rather, distance.

quote:

If the jacket expands from the heat in the bore does it expand outward loosening it`s grip, or does it expand inward gripping tighter??

I would say it would have to expand outward, loosening the core.

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Could be due to "Blow By", if there is not enough Pressure to cause the Bullet to completely obturate.

Trust me on this one - it's not blow-by. This a 224 bullet in a 223 bore! There is full contact of the jacket with the bore/gooves.

quote:

The SR 71 blackbird grows 6" in length during flight at mach 3 It's made of titanium and doesn't melt but it is definitely affected by air friction

That's why it's black - to radiate heat. They say the conopy gets so hot you cannot touch it!

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Berger did some research and found that the long bearing surface coupled with the long barrels and high velocity was heating the core enough to cause the jacket to shed in flight!

Actually hot enough to shed the jacket!

OK, I have some more insight gained on Sunday. In firing these loads I am talking about, sometimes the bullet would not exit the barrel! But they pushed out with a cleaning rod real easy! So why were they stopping in the barrel? Well, one of them stopped then shot out before the pressure could leak out. Would would happen whne the bullet stopped in the barrel is that the pressure would 'hiss' out slowly from the breach. This one that stop-started, hissed then shot out. I have no doubt the bullet is heating, expanding and the increased friction is enough to stop the bullet but as soon as the bullet cools, it comes out with a gentle push with the rod. I did say before that there is heat discolouration where the bullet has contacted the bore. Usually, one cannot see the actual contact surface due to rubbing but this bore does not do that - there is no copper fouling. Normally, I use lube and a paper cup in this rifle.

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BLOW BY -The hot gas will start to melt a lead nose spitzer type bullet in the barrel. As the bullet travels to the target, the air friction on the lead nose keeps it hot enough to keep sheading lead.

By 'starting to melt' doesn't nesessarily mean that melting is starting to occur - it is heating toward melting. The heating energy due to friction with the air is enormous but how much of that heat goes into the air?

I once read a book about John Browning, and IIRC, when he built his first machine gun for the army, it had to go through a very strenuous test. The Brass didn't believe in the concept, which was ahead of it's time, and developed a test designed to make the gun fail. It had to shoot something like 5000 rounds or so non-stop except for changing out belts of ammunition. Supposedly the barrel got red hot and was cooking the rounds off in the chanber even without the trigger pulled, and the bullets were melting as they came out of the barrel, but it did pass the test. Not really what you are talking about here, but interesting information nonetheless.

Most bullets which fail to hit their intended targets are generally operator error !.

However excessive velocity will melt lead bullets . Jacketed bullets which disintegrate or become

terribly unstable tend to over rotate thus causing their instability .* With increased velocity !.

Imagine keyholing on Steroids , once they become off centered of their rotating axis * most anything

is possible . Polymer tipped bullets don't melt . If your Rifle barrel is melting your bullets

you , A change Bullets , B change Barrels or C use it as a branding Iron ; because it's shot !.

I don't own anything faster than a 22-250 and have recovered many shots fired into water traps

at 100 & 200 meters none of which have disintegrated . Trap one they mushroom trap two captures

them in tact .

quote:

Originally posted by kcstott:
I don't know about melting but to much velocity also equal to many RPM's due to rifling pitch.
A bullet not rated for a specific velocity can be ripped apart by centrifugal force. I've seen it happen but only on twist rate higher then 1-9

I agree KC, bullets not designed for the velocities they are being used for, i.e. 22 hornet bullets in a 22-250 will cause failure by centrifugal force. The powder just behind the bullet actually acts as an insulator against the powder burning behind it in a controlled burn. Lead won't start stripping in a barrel until it hits 14-1500 fps I believe. Copper is a bit higher and usually gilded for that very reason.

I also agree with Craigster!

quote:

Trap one they mushroom trap two captures

them in tact .

Firstly, was there any sign of heat discolouration on any of them (where the jackets actually rode the rifling or bore)?
Secondly, how can I build one?

Although the thread is not about bullets melting - rather it's abouts bullet jackets expanding from the heat of friction - I would suggest that cast bullets really do melt in the bore. At least, a very thin skin melts. If a cast bullet runs out of lube, it might 'sieze' in the bore, that is, the surface layer in contact with the bore heats, melts and fuses with the bore. That would be called leading. The lead bullet can also smear in the bore without actually melting - also called leading. Then there is gas cutting of the cast bullet. No BS there - check this out;
This was fired in a two groove barrel with a bit of rust in the groove which caused a 'slight' gas leak. So, the suggestion that gas by-pass heats the bullet is probable! In fact, I now begin to wonder whether the undersize bullets can be inaccurate due to jacket heating by gas by-pass!

But, getting back to the original topic - the suggestion I made was that jacket heating and expansion might be responsible for some of the innacuracy we experience. This would be aside from over-spin failure and bullets melting in flight. (I want to know more about that one).

I finally have a picture of the bullet melted into cloth plus a bullet clearly showing the heat discolouration.

quote:

Originally posted by 303Guy:

quote:

Trap one they mushroom trap two captures

them in tact .

Firstly, was there any sign of heat discolouration on any of them (where the jackets actually rode the rifling or bore)?
Secondly, how can I build one?

Although the thread is not about bullets melting - rather it's abouts bullet jackets expanding from the heat of friction - I would suggest that cast bullets really do melt in the bore. At least, a very thin skin melts. If a cast bullet runs out of lube, it might 'sieze' in the bore, that is, the surface layer in contact with the bore heats, melts and fuses with the bore. That would be called leading. The lead bullet can also smear in the bore without actually melting - also called leading. Then there is gas cutting of the cast bullet. No BS there - check this out;
This was fired in a two groove barrel with a bit of rust in the groove which caused a 'slight' gas leak. So, the suggestion that gas by-pass heats the bullet is probable! In fact, I now begin to wonder whether the undersize bullets can be inaccurate due to jacket heating by gas by-pass!

But, getting back to the original topic - the suggestion I made was that jacket heating and expansion might be responsible for some of the innacuracy we experience. This would be aside from over-spin failure and bullets melting in flight. (I want to know more about that one).

Time to get larger cast with GC's my friend! :P Its too bad we don't live closer to hit the range and compare our mishaps, stories of gold metals, trophy bucks and bank busting fur baring critters.

What size bullets are you shooting?

One last thing for everyone. I feel like I m about to make a fool of myself.
But when shooting cast dose the bullet compress to the point that the bullet will widen in DIA? Example being .308 to .309/10?

quote:

Originally posted by 303Guy:
I finally have a picture of the bullet melted into cloth plus a bullet clearly showing the heat discolouration.

Looks as if it started to brake though when it stopped an finshed getting there with the temp. Looks like you like tight copper and lose cast! Shouldnt it be the other way around? Couldnt help that one Just dont come looking for me now!
But have you tried .223 dia instead of .224's?

quote:

But when shooting cast dose the bullet compress to the point that the bullet will widen in DIA?

I should wait for the experts to answer that one but in the meantime - yes! The bullet obturates to fill the bore but this does depend on peak pressure and strength of alloy. (Experts, please come in and correct me if and when necessary!) Excessive pressure can cause the bullet to deform into its lube grooves, making it inaccurate. Excessive latteral pressure between the bullet and the bore can cause excessive heating which leads to leading and it can cause lube failure or both. Apparently, surface temperatures of the bullet can get so high as to melt the bullet or galling of the bullet can occur due simply to the pressure. In a revolver with a forcing cone, a soft lead alloy bullet will expand as it leaves the chamber and get swaged back to bore size, sealing the bore and preventing flame cutting. I have found a harder lead to resist this obtuaration and actually end up with the 'groove' part of the bullet being cut smaller than the land part. Accuracy was better with the soffter alloy. Now I have seen evidence for this surface heating by bore to bullet friction.

Oh, jacketed bullets do the same, only, the jacket holds the core in place, but if the core obturation pressure gets high enough, it could cause excessive bore to bullet drag which might actually slow the bullet or raise chamber pressure significantly. But that's another debate!

And yes, I really do need to get those larger gas-checks! I have been expanding the rim of them just to get them to kinda seal! If I can't find some 8mm or 32 gas-checks I will have to make my own! But then, you saw the three shot 'group' from my other rifle. There were other shots fired at a different target that fell in the same 'group area'. they have a base diam of 8.05mm for a 7.95mm bore and taper down to 7.7mm at the nose for a 7.75mm bore. They engage the rifling at about 4mm from the nose.

Those two bullets in the pic are 218 bee bullets which I thought were .223 which is what the bore is supposed to be. Normally I shoot .224 55gr Hornady's in this rifle and they work great. There is full bore and land contact with the bullet.

Yup, it would be nice to get together at a range!

I have recovered the plastic tips from Nosler Ballistic Tips, from the wounds of animals from 308 and 300 Mag rifles. They showed no signs of melting.

I have also seen a wisp, or "tail" of lead from small calibre rifles marking the paper next to the bullet hole in the paper at 100 yards.

Also I have been hit with bullets and fragments of bullets and can say if they penetrate the skin and stick in your body, they are HOT!

quote:

... and can say if they penetrate the skin and stick in your body, they are HOT!

I would have prefered if you did not get to find out first hand! But since you did .... would you mind telling us how on earth that happened?

Gidday 303Guy,

Not meaning to be a smartarse but it would be pretty obvious, someone shot him.

Happy hunting

Hamish

quote:

Originally posted by 303Guy:

quote:

... and can say if they penetrate the skin and stick in your body, they are HOT!

I would have prefered if you did not get to find out first hand! But since you did .... would you mind telling us how on earth that happened?

I bet I can sum it up.
WAR I m glad he is here to talk to us

I know a few people who have been shot and they did not mention heat. The one poor chap took three hits from an AK, up close, in the chest. All he said is that it felt like hammer blows. Another fellow had a 15 shot Beretta 9mm emptied into him. He only mentioned the 'figure in white' and the 'bright light'. None of the others I know actually had bullets stop in them. Another fellow I knew once, shot himself in the guts with a 1911. The bullet exited from his anus. He knows this because they found the bullet under his butt. It had made three holes in his skin. In and out of a fold and in again with the infamous final exit!

I was lucky never to get hit directly by a bullet, it was always a ricochet and usually only a fragment stuck in my body.

303, I imagine if a bullet penetrates deep into the body there is enough "fluid" present and shock to the system to over ride any heat.

There have ben several studies done that suggest the worse the wound the less the body feels it, ie self preseveration takes over.

Also mind set is a big factor. Many people have gone down or even died when the would was not "that" bad, everything considered.

I was hit in the chest with one bullet fragment that was burning me bad,it has gone through my shirt and my T shirt. I reached into my shirt, part of the fragment was still sticking out as it had hit a rib and stopped, and pulled it out, and it burned my fingers as well.

All I can say is I am glad you here with us now!

Of course, a bullet that ricochet's or fragments on impact is going convert much of it's kinetic energy into heat - adding to the heat it already carries.

Speaking of dying from wounds that were 'not that bad', I once shot a wounded bushpig with a 12guage shotgun and it died on the spot - eyes wide open and not a twitch! When we butchered it we found no mortal wounds from the shotgun pellets. But it was tough enough to run off with both back legs broken from a shotgun shot! Go figure! This fellow who survived three hits in the chest from a AK - what can I say? OK, it was in the heat of battle so he would have been charged with adrenalin but so was the bushpig! (The second and third shot was fired into him while he was down from the first. Maybe it was those two he was refering to as being 'like hammer blows').

NE 450 No2: Were you getting those tails of something when you were useing boattail bullets. It could have been burnt powder gas pulled by the boattail of the bullet. At 50yds I was getting gas tails going out from the hole in paper in the direction of the rotation of the bullet. This was with Seirra 168 HPBT (no lead on outside of bullet) in a French Mas 36 but the same load with a 170 gr Rn flat base bullet left no tails.

/

quote:

I have also seen a wisp, or "tail" of lead from small calibre rifles marking the paper next to the bullet hole in the paper at 100 yards.

quote:

NE 450 No2: Were you getting those tails of something when you were useing boattail bullets. It could have been burnt powder gas pulled by the boattail of the bullet. At 50yds I was getting gas tails going out from the hole in paper in the direction of the rotation of the bullet. This was with Seirra 168 HPBT (no lead on outside of bullet) in a French Mas 36 but the same load with a 170 gr Rn flat base bullet left no tails.

Just bringing the two posts together! This is very interesting!

quote:

Bullets heating in barrel? How hot? only about 170 deg C ( 338 deg F)

About 7% of the total potential energy of the charge used is absorbed by the bullet.

The total exposure time for the bullet to the gas and barrel friction is only 1.5ms, after that the bullet actually starts cooling down.

True enough I would imagine. What I was getting at initially was that the heat from bullet jacket friction in the bore will be localized in the jacket material itself, meaning high localized temperature causing the jacket to expand loose from the core for a short time after exiting the muzzle, possibly resulting in loss of accuracy. If you have a look at the pic of the bullet you can see heat discoloration in the groove impressions. When I recovered the bullets soon after firing, they were hot. The second bullet in the pic actually fused itself to the fabric.

quote:

Originally posted by craigster:
I personally believe that the tales of bullets melting during their travel from breech to muzzle is caused by one or a combination of the following:

a. Bullshit
b. Old wive's tale
c. War story

Craigster,
You have some crow to eat. This has been document by photograph numerous times with .220 Swifts and .22-250s.

quote:

Originally posted by SR4759:

quote:

Originally posted by craigster:
I personally believe that the tales of bullets melting during their travel from breech to muzzle is caused by one or a combination of the following:

a. Bullshit
b. Old wive's tale
c. War story

Craigster,
You have some crow to eat. This has been document by photograph numerous times with .220 Swifts and .22-250s.

If that's the case, before I sit down to eat, I'd like to see the documentation and pictures.

Fat Albert

I was shooting a 223 with a 1 in7 twist and soft point bullets, Remington 55gr factory loads if I remember correctly.

It did not look like powder. The mark on the paper was sorta hook shaped, in the same direction of the twist.

It appeared to be caused by led spinning off of the bullet while it was in flight.

I have never seen it with a 308 firing 168 Sierra MK or the 165 HPBT Gamekings, and I have shot thousands of those.

Did not look like rifle powder.