Mixing different types of ammunition—especially a mix of good and not-so-good types—in a magazine assumes that it will be possible to fire additional rounds if something doesn’t work. But sometimes sh … tuff happens that makes that impossible.
Whenever the subject comes up, I think of something that happened in the notorious shootout between FBI agents and heavily-armed bank robbers in 1986. One of the agents, a member of the SWAT team and one of the best shots of the group, got one torso hit on the most dangerous of the bad guy pair, but very shortly thereafter his pistol was disabled by one of the BG’s rifle bullets. As the agent and his SWAT superior were focusing on the disabled gun, the BG walked up and killed both at point blank range. Although the shot from the agent into the BG’s chest was later determined to be nonsurvivable, it wasn’t enough to put the man down in a short time. A large number of shots were fired by the agents, including buckshot with a shotgun, most of which missed entirely, and of the ones that hit, most had no immediate effect on the bad guys. Two of the surviving agents were disabled by gunfire and another one lost his handgun at the beginning of the incident and was unarmed throughout.
During the Iranian embassy incident in London in 1980, one of the elite of the elite SAS operators had his vaunted HK MP5 malfunction just as he engaged the first of the terrorists.
Such incidents are hardly uncommon; several active killer events have come to an end because the murderer’s firearm malfunctioned and couldn’t be cleared. There are also many reports of police officers’ handguns malfunctioning or not being usable because of the officers’ injuries.
In other words, it’s not always possible that if an inferior bullet or load doesn’t neutralize a threat that we’ll have a chance to follow up with one that should have been used in the first place. Misses, malfunctions, inferior terminal ballistics, injuries to the good guy can all mean that “Oops: That
didn’t work; let me try again,” may not be an option. If I ever have to defend myself with a firearm, I’ll consider myself lucky if I get one good shot, and I’ll want it to be as effective as it reasonably can be under the circumstances.
And as for subsonic 300 Blackout loads, they are equivalent to shooting someone with a pistol caliber cartridge—except that their bullets are smaller in diameter than most defensive handgun cartridges’ bullets. If we’re willing and able to rely on a long gun for defensive purposes, why in the ever-lovin’ blue-eyed world wouldn’t we use a load with real long gun power and effectiveness?