I did a bunch of research a few weeks back and made an effortpost on nostr about it.

I wanted to know which handguns were most effective and if any could match the performance of long guns. I also wanted to understand the wounding effect of shotgun pellets and whether shotguns had some special wounding mechanism or were equivalent to a bunch of pistol shots.

I consumed whatever source I could find including autopsy reports, gel tests, battlefield reports, hunting videos and medical trauma care guides.

I found that typical handgun rounds are very close in effectiveness. In fact, I found that higher velocities can dissipate more energy elastically (through tissue stretching and deforming without permanent damage) and so a faster handgun round can actually penetrate less. 9mm for example was less likely to stop a threat in one shot than 380ACP, which has the same diameter but doesn't drive the bullet as fast.

Consequently I dismiss as suboptimal the handguns that virtually everyone claims are the best for self-defense. I think at 9mm or bigger you're adding a lot of bulk (to handle cartridge pressure) while getting very little or even reducing performance compared to a smaller gun. I think to improve over the most basic pistol performance you need 2,000+ fps, 250+ grain projectile weight, or high capacity plus rapid fire (to emulate the peformance of a rifle, shotgun or SMG).

I now carry a Glock 33 with ammo rated at 2,300 fps. Based on my research, I believe this should give me rifle-like performance. My home defense platform is an AR-type rifle, but I would probably take a full auto SMG with recoil mitigation (eg a proper MP5) over it for home defense or civil unrest, due to the shorter weapon length (and thus ability to move through doorways).

The answer on shotgun wounding was less clear. I think with greater spread (at longer range) each pellet is similar to a handgun round. However, I think when a sufficient mass (seemingly greater than 250 grain but data is sparse) impacts in a sufficiently small area (not sure how small), it exceeds the capacity of bodily tissue to stretch and dissipate damage. In other words, the fact that the pellets hit at the same time dynamically produces more damage than the exact same pellets hitting the exact same places, but spread over time.

The ultimate conclusion of my shotgun research was that slugs are more reliable manstoppers than shot. I now have my truck pump-action loaded with frangible rifled slugs, which get some of the non-penetration benefit of buckshot but with more consistent damage, much greater range, and the ability to be used in breaching. I think buckshot is overrated as a combat round, requiring a "flight control" type wad to keep the shots together and be effective, effectively simulating a frangible slug.

In terms of handheld shotguns, I considered .410 models such as the Taurus Judge, and concluded that 000 buck out of such a handgun is only more effective than the 45LC it can also fire at extreme close range (say, within 5 yards). Beyond that, the pellets spread out and are effectively 4 handgun rounds (but with much less control over placement).

So the only classes of gun I consider to be really sensible for self-defense are:

1) Pocket pistols in light calibers like 32ACP, 380ACP or 38 Special (for the most basic protection)

2) Specialty pistols/ammo reaching over 2,000 FPS

3) High capacity machine pistols (eg Glock with a switch)

4) True SMGs

5) True shotguns (with shot for drones or slugs for men)

6) Intermediate rifles (AR, AK, etc)

For *offense* you can bring in belt-feds, DMRs, and snipers.