Bullet Performance

Bullet Fragmentation

Fragmentation in modern centerfire lead rifle bullets is a direct result of their formulation to be a controlled-expansion projectile. They are specifically designed so that the frontal portion of the bullet consistently and reliably expands to almost twice their original diameter.
This design does a couple of things to ensure a quick and humane kill:
  1. It delivers a hydrostatic shock wave that travels out from the bullet’s path and into the animal’s body that has received the bullet, causing significant damage to internal organs and bones.
  2. It ensures that when the bullet tumbles through the body, the increased diameter and sharp edges of the expanded bullet causes more internal physical damage to the animal.
However, one other consequence of a rapidly expanding lead bullet traveling at more than twice the speed of sound is that some of the soft metal itself erodes away from the frontal section of the bullet as it strikes and travels through the animal.

Lead bullet fragmenting as it travels through the body

This .270, 130 grain Remington Core-Lokt bullet was discharged and retrieved and found to have lost 32% of it's original mass due to fragmentation. Contrast this bullet with a .270 cal Barnes Triple Shock copper bullet at the bottom of the page.

 

 

Another Core-Lokt bullet was fired into ballistic gelatin and then x-rayed. The non-lead bullets depicted above and below lack the fragmentation of the lead-core bullet in the middle.

 

 

 

 

Why Lead Fragments Matter

It's this fragmenting characteristic of lead bullets that is cause for concern for wildlife and humans who eat any portion of an animal shot with this type of bullet. While efforts have been made to retain the expanding characteristic of lead bullets, but eliminate the fragmenting aspect (e.g. special bonding of the jacket to the bullet core), none have been entirely successful in this regard.

The facts are clear based on valid scientific studies that have been conducted (Minnesota DNR, The Wildlife Society Bulletin) - full text (PDF)

Lead-core bullets WILL fragment to varying degrees depending on:

  1. Where the bullet strikes (Bone will cause bullets to break apart much more than flesh/organs).
  2. Composition of bullet (soft point bullets fragment the worst; bonded-core fragment the least).
  3. Speed of the bullet (higher muzzle velocities mean greater fragmentation, all other things being equal).

Lead Fragments in Animals

The x-ray below is of a mule deer that had been shot with an unknown caliber center-fire lead rifle bullet on the Kaibab Plateau in Arizona. The bullet struck the spine and then completely disintegrated into hundreds of various sized fragments. When this deer was found, a number of eagles, condors, turkey vultures, and ravens had gathered around to feed upon the carcass. Luckily for these scavengers that had fed on it, when the deer fell, the side with the bullet entry wound was facing towards the ground and had been unavailable to feed upon.

Neck-shot Mule Deer

Dark spots are lead bullet fragments

 

 

 

 

 

 

Close-up of photo from above. Note the fractured spine and hundreds of small lead fragments.

 

 

 

 

 

 

 

 

More Lead Bullet Fragmentation in Whole Animals

Summary of findings from scientific paper listed above that counted the number of lead bullet fragments in whole carcasses and gutpiles of white-tailed deer shot with centerfire lead-core rifle bullets: www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0005330

Rim-fire Bullets and Fragmentation

Rim-fire bullets, such as .22 LR, travel at slower muzzle velocities, yet also fragment to a surprising degree. This picture shows a yellow-bellied marmot (a large beaver-sized rodent) that had been shot and then donated to a raptor rehabilitation facility in Montana for feeding to birds being held there. The owners of the rehab facility had heard of lead bullet fragmentation and as a precaution, had the animal x-rayed. As you can see, it was fortunate that they did this, because the marmot is riddled with lead bullet fragments and if fed to a hawk or eagle, fatal lead poisoning could have resulted.

Yellow-bellied marmot shot with a lead .22 caliber bullet

 

 

 

 

 

Non-lead Bullet Alternatives

Barnes Triple Shock Bullet - .270 caliber

Luckily, newer alternatives made of either 100% copper or copper-zinc alloys exist that expand similarly to lead-core bullets but without the extensive fragmentation.

Visit here to get more details (.xls)

 

 

 

 

 

 

 

 

Bullet Expansion and Energy Transfer

Rapid and controlled expansion of a rifle bullet is necessary so that the kinetic energy present in a speeding projectile is transferred into the tissues of the animal being hunted. Non-lead bullets do not fragment like lead-core bullets and therefore, often pass through the animal. Some suggestions have been made that this will result in insufficient energy transfer because too much of the bullet’s energy is “wasted” if the bullet exits. In order to test this assertion, we compared energy transfer for both lead and non-lead bullets and found that the differences were small. This is because since the non-lead bullets exit at a slower velocity compared to their entrance velocity, the bulk of the energy has already been expended in the animal. This is important because bullet energy is computed with a formula that takes the bullet’s speed and squares it, so that a relatively small change in velocity results in a much greater change in bullet energy.

Bullet energy was compared by firing bullets into a 10” thick ballistic gelatin. The gel block was chosen to simulate the resistance a bullet would experience when hitting a small-bodied animal like a black-tailed deer. A digital chronograph was used to measure the incoming and exiting velocity of the various bullets fired.

Chronograph set up in front of gel block to measure incoming velocity

 

 

 

 

 

Chronograph set up to measure bullet velocity as it exits the gel block

 

 

 

 

 

 

We then used the following formula:

Energy (ft-lbs) = {Bullet weight (grains) X Velocity (ft/sec)2 }/ 450450

We tested the following bullets in .270 Win. and .30-06 Spr calibers:
Lead-core: Remington Core-Lokt
Nonlead: Barnes Triple Shock and Tipped Triple Shock, Remington Copper Solid, Nosler e-Tip, and Hornady GMX


Graph comparing energy transfer for lead and nonlead bullets

As shown in the graph, when bullets were fired into a relatively thin 10" ballistic gel block, non-lead bullets expended similar amounts of total energy as did the lead bullets. Also, it's worth pointing out that a 110 grain .270 cal non-lead bullet expended MORE energy than a heavier 180 grain, 30 cal lead bullet. This was due to the 110 grain bullet entering the gel at ~3100 ft/sec, which gave it a proportionally much greater amount of kinetic energy than a slower, but heavier lead bullet.