Hammer Bullets vapor trail

[shinbone]

While shooting at the range yesterday morning, atmospheric conditions were right for the Absolute Hammer 151 gn bullets to produce a vapor trail. This out of a 30 Nolser. This was a first for me, and it was fun to watch.

Guns - Randall Cherry

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[lancetkenyon]

Not a vapor trail.

It is the well known "Hammer trail". The cutting oil left in the meplat makes this happen.

And yes, it is cool to witness it happen.

 

[shinbone]

"Aerosolized" is probably a better term(?): by being spun and flung out of the bullet's cavity-tip spinning at over 300,000 rpm, the oil particles become so finely divided that the particles are suspended in the air.

Just thinking out loud: "aerosolization" is dependent on particle size, i.e., the particles must be made small enough that they can be suspended in the surrounding gas. Meaning with sufficient muzzle velocity and barrel twist, the "Hammer trail" should always be seen. But its not. Anyone got any thoughts on why the Hammer trail is visible only under certain atmospheric conditions? Perhaps the aerosolized oil is always created but invisible because the oil droplets are too small to be seen with the eye, but may condense into larger, visible, droplets under the right barometric/humidity/(something else) conditions?

(edited to correct the rpm number)

 

[Coyote Shadow Tracker]

I see better vapor trails when there is high humidity. Shooting .338LM with 300 OTM at a mile + and you can see the vapor trail and the bullet DROP into the target.

 

[Phil Rizzo]

"Aerosolized" is probably a better term(?): by being spun and flung out of the bullet's cavity-tip spinning at over 100,000,000 rpm (103,536,000 calculated for this load), the oil particles become so finely divided that the particles are suspended in the air.

Just thinking out loud: "aerosolization" is dependent on particle size, i.e., the particles must be made small enough that they can be suspended in the surrounding gas. Anyone got any thoughts on why the Hammer trail is visible only under certain atmospheric conditions? Perhaps the aerosolized oil is initially invisible because the oil droplets are too small to be seen with the eye, but may condense into larger, visible, droplets under the right barometric/humidity/(something else) conditions?

You have a special twist rate?

 

[quigley257]

Assuming you're running a 1/10 twist in the barrel, your RPM would be 258,840 RPM. Bullet RPM is MVx720/twist rate.

 

[shinbone]

I had used the twist rate incorrectly when calculating rpm. I changed my post to a generic "300,000 rpm."

That is still pretty fast, and I am still thinking the oil in the tip cavity is being aerosolized.

 

[quigley257]

3595x720/8=323,550rpm

 

[quigley257]

Even monolithics would become liquid at 114million rpm. Most cup and core bullets don't handle much over 350,000 rpm.

 

[shinbone]

fixed my error in the rpm number.

 

[T3ninja]

 

[shinbone]

T3ninja - cool photo!

 

[Huntnful]

I don't shoot them anymore because the BC's were so inflated that it irritated me lol. But I shot them for a season.

 

[01Foreman400]

Not a vapor trail.

It is the well known "Hammer trail". The cutting oil left in the meplat makes this happen.

And yes, it is cool to witness it happen.

They don't go through a wash before they are sent out?