There’s a concept called ‘common knowledge’ or ‘colloquial wisdom’ that persists in virtually every field of human discussion with institutional knowledge. This can have several definitions; the most common one is a variation on the theme that there is certain knowledge or factual tidbits that persevere in a knowledge-based environment without good science behind them.
Common knowledge is dangerous.
Common knowledge persists even in the face of a lack of scientific data. People will fail to go back and challenge common knowledge; or what’s worse, is that they’ll refuse to accept any scientific data that does so. It becomes entrenched dogma.
One of the most common ‘pearls of wisdom’ is using birdshot or worse, rock salts, as a tool to deal with armed aggressors. This is the sort of common knowledge that is not just wrong, it’s dangerously wrong.
Birdshot, even at very close ranges, utterly fails to deliver the sort of penetration that is absolutely essential for effective tactical problem-solving. Remember FBI demands as minimum of 12″ of penetration in order to consistently and effectively hit the internal organs and blood bearing systems. #8 birdshot at close range will deliver on the order of 4-8″ of penetration at best on bare gelatin. Add in a few layers of denim or a thick leather jacket, and penetration drops to 3-4″. Lots of ugly surface wounds, but extremely survivable.
Rock salts are bad for all the same reasons. Massive, ugly surface damage and little to no wound trauma. Remember, there is no such thing as shooting to wound. If an intruder has entered your home in a violent or tumultuous manner, then (in many states) you have a legal justification in employing a firearm to protect yourself from harm. Laws about castle doctrine and your duty to retreat or provide warnings may vary– know your local laws and regulations.
If you don’t have a legal justification to use a firearm in self defense, then you have no legal justification to use a nonlethal firearm. The law rarely distinguishes between lethal and nonlethal ammunition– ‘my ammo intentionally sucks’ is not a viable defense.
If you have serious concerns about overpenetration, collateral damage or recoil management, #4 buckshot at 1300 FPS flirts with the lowest edge of effective tactical performance and offers somewhat mitigated penetration issues. #4 Buckshot will still travel effortlessly through multiple interior and exterior walls and retain lethal velocity. This is why it’s a very bad idea to rely on the ‘spread’ of a shotgun as compensation for having bad aim. You are accountable for every projectile that leaves your firearm.
The preferred round of many tactical experts may not be what you think– currently #1 buckshot (particularly the Federal LE-132-1B) in a good, tight pattern is gaining tremendous popularity among law enforcement personnel. The slightly smaller payload of 16 .30 caliber pellets actually increases the total wounding surface area by nearly 30% over 8-9 .32 caliber pellets in #00 buck, without sacrificing necessary wound trauma cavity.
Pop your granddad’s old #9 birdshot out of your home defense shotgun and toss it in the range bag where it belongs. Shoot it up breaking clays or use it for practice ammo. But don’t rely on it to protect your life in a violent life-or-death altercation where tactical problem solving calls for a firearm.