is copper jacket spinning around lead core during flight

[BradyT88]

I have a couple things I think I can add to this. I recall reading somewhere that when Hornady released the new ELD series bullets, one of the improvements was making the tips out of a more heat resistant material than their older bullets used (the A-max I believe). Supposedly when shot at long distances (800+ yds) the friction from wind drag of the bullet cutting through the air would heat the tips up enough to slightly melt and distort them enough to affect the flight of the bullet (the ELD's are not supposed to have this problem). I don't know whether the tips or lead have a lower melting point but this would imply that the heat generated by air friction over a few seconds is greater than heat generated during the initial launch of the bullet from the muzzle.

As for blowing up bullets, I have only ever blown up 2. The first was shooting some .500 cal Berry's copper jacketed bullets. These 300 gr bullets were likely meant for a 50 AE or 500 S&W handgun. I was shooting them in a rifle with an 18" barrel. I knew the max velocity was 1400fps or so and that I would likely be going faster so I used AA#2 powder and the minimum load. I shot them through a Caldwell and they were going 1800+ fps. When I looked at my target at 50 yards I had 2 holes and a pattern that looked like it was peppered with a 410 shotgun. One of the 3 bullets must have ripped apart just before impacting the target.

The 2nd one I blew up was a couple weeks ago. I was testing some 50gr Vmax in my 223 Rem with a 20" 1:8 twist barrel. I did 5 three shot groups moving up in 0.3gr increments looking for pressure signs. I never got any pressure signs, but the very last shot my Labradar threw a "failed to track bullet" error. When I checked the groups I only had 2 holes on the paper at 100 yards for that last 3 shot group and I knew there was no way I missed the entire cardboard target. Checked my bore and no bullet stuck in the barrel. I checked the math and with my 1:8 twist and clocking them at just over 3400 fps those bullets were doing over 300,000 RPM. I called Hornady and they said that it was extremely likely the bullet blew up since those thinner jacketed varmint bullets are not rated to handle that kind of RPM.

 

[DMP25-06]

Do any of the members/contributors here on LRH know of , or have access to studies that may have been conducted to determine , or theoretically determine ( Scientific Wild A . . Guess ) the temperatures that a bullet-in-flight generates by atmospheric friction ? Or the temperatures generated within the barrel ( true friction ) from physical contact between the bullet and barrel ?

I would presume that such a test would require some very special , sensitive ( I hate using the over-used word "sophisticated" ) testing equipment .

DMP25-06

 

[shootallday]

Do any of the members/contributors here on LRH know of , or have access to studies that may have been conducted to determine , or theoretically determine ( Scientific Wild A . . Guess ) the temperatures that a bullet-in-flight generates by atmospheric friction ? Or the temperatures generated within the barrel ( true friction ) from physical contact between the bullet and barrel ?

I would presume that such a test would require some very special , sensitive ( I hate using the over-used word "sophisticated" ) testing equipment .

DMP25-06

I would think nasa has some formula to get a idea, they knew they needed heat Panels on there stuff before the ever launched.

 

[Rflshootr]

So if the core melted, why do you get jacket separation that many times the jacket is found in an animal, but the core passes through and makes an exit wound? How would molten lead continue to travel through without dispersing to nothing? Maybe there is a reason that they make the base of the jacket thicker then the sides? Way back when, Sierra and some other bullet makers used to make their match bullets with an open base where you could actually see the lead core. If the core melted, wouldn't the lead run out while the bullet was in flight? Actually, aren't FMJ bullets still make like that? Think about it.

 

[baldhunter]

I saw some video of a Hornady Amax bullets blowing up a short distance away after they were shot.From what I remember it was the ones with the original red tip.I don't think it was all of them,just certain ones at certain velocities this was occurring.That was the reason Hornady changed the tip to a different plastic and this was before the ELD line of bullets.I guess if the jacket is thin enough they could explode in flight,but as for the lead inside the case becoming molten and spinning inside the copper jacket,I don't think so.It takes a lot less heat to melt plastic than lead.Look closely and you can see the green tip from a 165gr Nosler Ballistic Tip ran at 2900fps from a 30-06.It's right near the top of the wound channel.

 

[DMP25-06]

I would think nasa has some formula to get a idea, they knew they needed heat Panels on there stuff before the ever launched.

I don't think that the current administration will allow NASA , oh SH-T I mean SPACE FORCE , to do any testing of Bullets-in Flight , submitted by we , the PEONS .

 

[Radman]

I would think nasa has some formula to get a idea, they knew they needed heat Panels on there stuff before the ever launched.

Took me over an hour to find it in my Book of Cheat Sheets but I did once read that, "As chamber pressures increase so do initial temperatures which can reach as much as 4500°-5500° F." However I remember reading once that the average detonation temperature was something like 3500° F. If any of this is true, (who trusts any news source today?), this is of course concentrated at one point & quickly absorbed by various metal components as well as most of it is likely compressed OUT of the barrel.
Hey...just telling you what I read "way back when".

 

[baldhunter]

Watch the Amax explode

 

[baldhunter]

Hornady video about the tips melting

 

[emp1953]

The NASA angle is intriguing. The Space Shuttle entered the atmosphere at 24,900 feet per second. They've been dealing with the physics of this kind of stuff for decades.

 

[shootallday]

My dad built a 7mm rum when they came out on a is Enfield action. We had quite a few bullets blow up, there would be a big puff at about 40-50 yards.

I would think if the lead could melt I think it wouldn't have much affect, the hole once a mass is moving thing.

 

[DMP25-06]

Watch the Amax explode

I hate to be the non-believer of this video , BUT ........ the 162gr A-Max took more elapsed time to go 20 yards and "Explode" , than the Accubond took to shoot , impact at 200 yards , and the sound of impact return to the camera's microphone .

I have read about , and seen videos , of the A-max bullets , in various calibers , disentigrating when shot at high velocities from fast-twist barrels , but it was always nearly instantaneous after hearing muzzle blast , and no audible sound of explosion . No discernable lapse of time between hearing muzzle blast and bullet break-up , especially at 3350 FPS .

And Hornady said that the thin jacket of A-Max contributed to breaking apart at high velocities and spin rates .

 

[shootski]

Habu (SR-71) flew at Mach 3+ and the leading edge temperature never exceeded 600° F (316° C) on long missions. It took minutes at speed for the windshield exterior temperature to get above 450° F (232° C) not enough to even melt Pb (Lead) but they used a Titanium Alloy skin and a man-made Quartz outer layer for the windshield.

 

[Professor Doolittle]

This is an interesting theory .

I happen to think along a different viewpoint about the lead cores melting inside the copper jackets .
For many years I hunted with a 7mm Remington Magnum shooting 150gr Nosler Partition bullets at a chronographed velocity of 3250 FPS average , out of a 1:9.25" twist barrel , that would mathematically achieve a rotational speed of 252,972 RPM's . THAT SHOULD GENERATE SUBSTANTIAL HEAT AND CENTRIFUGAL FORCES , according to the theory expressed above.

If you are familiar with the Nosler partition bullets , and you examine a cross-sectioned partition bullet , you will see that the copper jacket is drawn in a shape that resembles the letter H , with lead being above and below the partition , with a visibly exposed lead tip , and a visibly exposed much broader lead base with the copper jacket minimally closed around edges of the lead base to hold it in place .

I have only recovered 3 of these Partition bullets from inside animals (all others exiting) , and in all 3 recovered bullets only the jacket and rear core were found . The lead inside the rear of the Partition looked to be perfectly smooth , with no evidence of heat deformation from being exposed to the blast heat . The surface of the lead looked just as smooth and unmarked as the surface of a new Partition bullet out of a new box .
If all of this heat is generated , shouldn't the lead base have shown markings indicating the beginning of melting ?


Now , after having listed my personal experiences and observations , I will post my theory about the heat from the burning of the powder effect of heating the bullet/projectile .
I think that the bullet is being pushed/propelled out of the barrel by a pressure wave created by the burning rapidly expanding gases generated by the burning gunpowder .
When i have watched extreme slow-motion video of bullets exiting the muzzles of different firearms , the bullet is always several inches ahead of the flash/fireball of the burning powder.

Interesting observation, but there's no pressure that's standing apart from heat in a gas, we naturally think of heat and pressure as two different things but they're not. They're the same one thing looked at from two different perspectives. When contemplating a gas the only difference is that heat is the total kinetic energy of the atoms going every which way randomly whereas pressure is the total kinetic energy pushing against a surface, the container wall. Heat is total kinetic energy of randomly directed gas atoms, pressure is the kinetic energy they're imparting to a surface bounding the gas, but they are both perspectives on the kinetic energy of the atoms.

Now as far as why does the visible muzzle flash seem to follow long behind the bullet, well the bullet is a single small thing that's long gone whereas the hot gas takes more time to exhaust. When the bullet is leaving the muzzle the gas is just beginning to exhaust. Like puncturing a car tire, it doesn't instantly go flat.

But you bring up a good question, it would be interesting to know what percentage of the total visible light released by the gunpowder reaction makes it outside the barrel following the bullet. That muzzle flash is late burning gunpowder and possibly superheated gases whose outer electrons are dropping into a lower ground state releasing photons, not trapped light finally being allowed to escape. The visible light released in the cartridge will be reflected thousands of times before the bullet leaves the barrel until the steel atoms absorb it raising the temperature. The carbon will absorb a lot of it, that's why carbon is black, it doesn't reflect light. The photons bounce around until they are absorbed by various atoms of the steel and brass and when they get absorbed the kinetic energy increases, helping make the barrel hot.

THIS IS JUST MY OPINION . I am NOT trying to argue with anyone on this subject .


One final observation about the theory of the melting of the exposed soft lead tip of spitzer shaped bullets while in flight .
While hunting in the mountains of Colorado in 1984 , I once found a bullet that had fallen to earth , not having hit any animal or object , just laying on the ground . The copper jacket was scribed by the lands of the rifle barrel , and the forward tapered nose was slightly bent , flattened , and scratched on one side from falling from the sky to the earth , and the exposed soft lead tip was still there on the tip of the bullet , although bent and scratched also .
I kept this bullet as a trophy/memento from my hunting trips , and I have it stashed away somewhere .

DMP25-06