Home Forums Hunting & Shooting Ask The Gunwriters Temperature of Fired Bullet

I just viewed a video of an SR-71 Blackbird spy plane. It stated the plane flew at 2,200 mph (Mach 3) and the surface temperature reached 1,000 degrees due to friction.

Has anyone ever determined the temperature of a high-velocity bullet when it reaches it's maximum speed? Years ago I remember reading that a .270 bullet rotates 180,000 rpm at it's maximum.

When you think of all the physical forces exerted on a fired bullet, it's amazing they can be so accurate and effective.

A bullet burns when it penetrates your body. So it is hot. How much I don't know.

From a 10 twist at 3100 fps, I think' it's faster than that. Anyone know the math?

Gotta be below the melting point of lead .

Friction applied steadily over a long period of time.

Think about passing your fingertip through a candle flame vs. holding it in the flame.

12/10x60x3100=223,200rpm

DT: Thanks!

Air friction yes. Barrel friction no.

Do not pick up bullets in the butts if you work back there.

I had a conversation with Bill Stegers one time about bullet design. He said that using HIGH speed photography Speer discovered that the bullet tip of exposed lead melted from air friction and that was one reason he used a no lead exposed design for his Bitteroots. That may explain some of why BC changes as the bullet goes down range; the tips melt off.

So yes they do get HOT.

How do plastic tipped bullets make it downrange intact?

267 C or 513 F according to this study using an infara red camera on a 5.56 M16 projectile. This is under the melting point of lead if memory serves.

It appears that the bullet heats up from being squeezed through the bore by a cloud of super hot expanding gas and actually cools as it travels downrange.

Where is my prize?

www.flir.com/uploadedFiles/speeding-bullet.pdf

pure lead

Melting point, 600.61 K, 327.46 �C, 621.43 �F .....

Alloys would melt at a higher temperature,

Gotta love the internet!

Could be that a high intensity magnum might have a higher temperature than the 5.56 bullet. However in the fractions of a second we are talking about the surface heat would be unlikely to penetrate far.

Note that the bullets cooled as they moved away from the gun.

The melted-tip theory of ballistics turned out to be a myth, created by thge limitations of the photography of the day.

I have seen cores melt, at least partially, in varmint bullets on very hot days, when shot through barrels that are already smoking hot. Often the bullets will zig off in a new direction, and sometimes they even come apart in the air. If you shoot them at paper there'll often be whirls of melted lead around the bullet hole.

But those are relatively small bullets, with thin jackets and very soft lead cores. And it takes some pretty high velocity to do it. One day in Kansas when it was around 100-105 degrees, Ron Spomer and I were shooting prairie dogs with the then-new Winchester USA brand of ammo, with very thin-jacketed 45-grain hollow-points. Ron was shooting a .22-250 and I was shooting a .223, and every time his barrel got REALLY hot the rifle started spraying bullets, while my .223 kept shooting very well. Turned out the cores were melting in the .22-250.

I have seen what looked like a melted swirl of lead from a .220 Swift. This is different from a trace or air disturbance as the bullet goes through the air.

i would think the plastic tipped bullets would have a lot less friction with the air than a more blunt lead tip. so they would build up less heat, yes?

Exactly.

I picked up a spent 270 grain hornady I'd just fired from my .375 H&H and it burned the [bleep] out of my fingertips. I won't forget that any time soon.

Tom

I believe I read some reports where the length of the barrel can affect the temperature of the bullet. I think a 500 degree bullet has some bearing on its performance when it strikes the target too.

I'll bet that a round fire with a sabot will have slightly different characteristics that a normally engraved bullet. I am not gonna be the one holding the infrared thermo gun trying to measure those suckers as they go by though!!!

They use a high temperature plastic in the point. Remember that the SR-71 had a saw-toothed leading edge that was filled with high temperature plastic that heated up pretty high, but did not deform. The saws tooth leading edge was designed to reflect and minimize incoming radar signals.