What's a hollow point?

I recently testified to a very specific type of ammunition called the R.I.P. (radically invasive projectile) from G2 Research. One interesting part about firearms examination is learning about all the various designs of ammunition, and it's another aspect that is constantly changing as ammunition designers try to get specific types of performance. One design choice for ammunition is loading a hollow point bullet into the cartridge (see the previous post about the terminology of ammunition if I'm losing you).

Left to right: unfired hollow point bullet, cartridge with flat nose TMJ bullet, and cartridge with round nose FMJ bullet

Looking at the photo, you'll see a jacketed hollow point bullet (JHP) on the left, a flat nose total metal jacket (TMJ) bullet in a cartridge, and a round nose full metal jacket (FMJ) bullet in a cartridge. The obvious design difference is the scoop taken out of the top of the bullet. This is where the "hollow" in hollow point comes from. You can also notice multiple small vertical gouges or cut marks going from the top of the bullet partly down the ogive of the bullet (sloped sides).

What are these design choices for? The skives are designed to create weak points in the nose of the bullet. The hollow point is designed, that on contact with the target, to fill and create outward pressure on the inside of the hollow point as it continues through the target. This outward pressure (ideally) will cause the bullet nose to split at the skives. The hollow point can get filled with materials that will prevent the bullet from opening as designed. Heavy clothing can be one of these items. Once the bullet nose breaks at the skives, the bullet nose continues to peel back, much like peeling a banana. Each section (areas between the two skives) is called a petal. In the photo, that bullet would have six petals peeled back, if the bullet expands as designed.

The point of having the petals open and expand is to create a large surface area shortly upon entering the target, transferring more force into the interior of the target. If your target is a person, this translates into a larger amount of force being transferred into surrounding organs, creating more injury to the target and a more lethal bullet. This also creates the secondary effect that the bullet is more likely to stop within the target, instead of traveling completely through the target, which is more common with a FMJ bullet, decreasing the chance a secondary target in the background will be hit.

The R.I.P. bullet I was testifying about has a similar design, but instead of petals bending backward and staying attached to the bullet, the bullet fragments into "trocars" with the intent to cause injury to more internal organs. Ultimately, hollow point designs are intended to be more deadly, and used in self defense or hunting applications to kill more quickly. In the case of this testimony, one argument was being made the ammunition was picked specifically because it was more deadly for a planned homicide. The other side made the argument that the ammunition was bought specifically for being good self defense ammunition.

Snipped from the website https://g2rammo.com/

Either could be true, but neither would be able to make their argument without understanding the basics of hollow point bullets.

If you want to know about other types of bullets, put a comment on the post and I will create a follow up post.