I’ve been giving G2 Research absolute Hell for their R.I.P. handgun ammo from the very beginning, and with just cause: it’s over-hyped and insanely marketed, and at the same time, completely under-performs.

As I’ve argued time and again, you can’t change the laws of physics. They are physical laws for a reason.

The R.I.P.’s tiny little 8-grain shards (they call them trocars, after the medical tool) and a forty-something grain base simply lack the mass to cause the sort of damage needed to quickly and reliably stop a fight by destroying enough tissue in vital organs. This is not to say that R.I.P. bullets won’t leave nasty, generally shallow wounds that cause a psychological stop, or eventually cause a stop from blood loss, but these and other “miracle” fragmenting pistol bullets of the past simply don’t have a good track record in the real world under a wide range of conditions. They lack the mass to destroy enough tissue to get the job done.

That doesn’t mean that fragmenting ammunition is a bad idea, just that fragment handgun bullets will either need more mass or velocity (or both) to have the desired disruptive potential.

Shotguns have a much larger bore and don’t have that mass problem, but can have penetration issues depending on the choice of ammunition.

Birdshot doesn’t tend to penetrate well enough, while many of the larger buckshot loads and slugs tend to be effective, but the buckshot can spread so that pellets on the edge of the pattern might miss the target and become a threat to those in other rooms downrange, and solid slugs are also well know for boring through bad guys are continuing on their merry way.

Winchester is attempting to address those issues with a just-introduced segmenting 20-gauge slug that sounds like it will get the job done.

Winchester® Ammunition first launched its Defender® line of personal defense ammunition five years ago, providing responsible citizens with the most reliable ammunition to protect their homes and families. Winchester continues to add to the line up of innovative ammunition for personal defense with a 20 gauge segmenting slug.

The Winchester Defender Segmenting Slug combines all of the advantages of a slug and buckshot, while eliminating the need for two different rounds. This greatly simplifies the shotgun platform, allowing one round to be used for all situations. The round is designed to compensate for aim error over traditional slugs. Upon impact, the slug segments into three equal projectiles – delivering greater knock-down power than traditional buck shot loads, improving aim error and reducing the chance of stray projectiles in confined spaces.

The segmenting slug is designed to split into three pieces as it enters the target eliminating the chance of the slug passing through and striking additional objects in its path.

It’s an interesting attempt at solving a specific self-defense problem. Rob Pincus talked about the slug and shows its effect on a gel block towards the end of this video from Media Day at the Range during SHOT Show 2014.

The 20-gauge 2 3/4″ shell packs a 3/4-ounce (382 grains) slug that leaves the barrel at 1,600 feet-per-second which breaks apart on impact into three 125-130-grain fragments that each create a substantial permanent crush cavity 12″-14″ deep over a 6″-8″ spread in bare 10% gelatin.

It puts three fragments—each the weight of a 9mm pistol slug—into the target and disrupt a comparatively large amount of tissue, while still posing less of risk of a miss and hopefully posing a lower risk of over-penetration when compared to traditional slugs.

Fragmenting ammunition can work, you simply need to have the mass in each slug to disrupt enough tissue at critical depths.