07/28/2022
9mm vs 5.56
Up front, this post won't be about handguns vs rifles, this is about pistol caliber carbines vs 5.56 rifles for home defense, keeping all things equal. For a post on handguns vs rifles vs shotguns for home defense, head over to this post, linked here: https://bit.ly/3xtU0XM
Now back to the topic at hand. In general, I almost universally recommend 5.56 over 9mm, assuming you keep all things equal. And this remains true for nearly all pistol rounds. So when I say 9mm in this post, keep in mind that this includes .45acp, .40S&W, .380acp, and most other pistol caliber carbines.
Comparing a 5.56 AR to a pistol caliber AR, I find the pistol calibers to fall short.
In comparison to a 5.56 AR, a pistol caliber AR gives you:
1) A gargantuan reduction in terminal effectiveness. Handgun rounds just kinda suck at quickly stopping people. In comparison, 5.56 is devastatingly effective at stopping people quickly.
2) A reduction in capacity.
3) An increase in ammo weight while often coming with an increase in the weight of the gun itself. 5.56 AR's are pretty darn light, while 9mm AR's tend to be a bit heavier (more mass for a blowback bolt, heavier barrel, etc)
4) Minimal reduction in recoil
5) Less damaging to unprotected hearing
6) Many PCC's take mags that are significantly harder to find than normal 5.56 AR mags. Only the ones that take G***k mags solve this problem.
7) Almost all handgun rounds and loads go through FAR more walls than 5.56 loads do. For a post explaining why, hit this link: https://bit.ly/TSGwallpen
8 ) Reliability. Pistol caliber AR's aren't known for their reliability. On average, PCC's are less reliable than intermediate caliber rifles.
Other than being less damaging to hearing, which is far better solved by getting electronic hearing protection, the one area where a pistol caliber carbine really shines over an otherwise identical 5.56 rifle is when you get into shorty pistol/SBR territory.
When you have a 12" barrel, go 5.56. There is no reason to go 9mm. But when you're aiming for like a 5" barrel, that's where the pistol calibers shine. And again, they shine not because pistol calibers are awesome from that barrel length, but rather because 5.56 from a barrel that short is more neutered than Bob Barker's dogs. For a post on 5.56 barrel length, head here: https://bit.ly/3IHwRmz
Anyway, when you're using a super short barrel and getting less than 2000fps from 5.56, you're dealing with .22mag to .22lr levels of performance. And when you've neutered 5.56 that badly, just go with a PCC instead. While 5.56 really yearns to have a full rifle length barrel, pistol cartridges are unsurprisingly perfectly happy from pistol-length barrels. Anywhere 3 inches and above is perfectly serviceable for most handgun cartridges.
That said, you are still probably better off with a 16" 5.56 AR rifle than a 5" 9mm AR pistol, much less a novelty 5" 5.56 AR pistol. I think people have an illogical obsession with shortening their barrel, even if it means being less effective and having a worse gun. A 16" AR really isn't that hard to handle. If you really do want a shorter gun, then get a 5.56 bullpup. A bullpup with a 16" barrel will be shorter than an AR pistol with a 7" barrel. Or you could just deal with a 16" AR. Yeah, they're less tacticool and they don't come with bragging rights, but they are more effective.
Anyway, back to PCC's vs rifles. Other than reduced muzzle blast, cheaper ammo, and being viable in super short barrels, I don't see any reason to choose a PCC for home defense. But exceptions come in when you deviate from the norm, when you are no longer comparing apples to apples.
As a previous post explained (linked here: https://bit.ly/TSG57x28), a 5.7x28 PS90 can offer reduced muzzle blast and significantly reduced recoil while also being massively shorter and easier to wield than an AR. The only sacrifice is in terms of terminal performance, which is more in line with PCC's than with rifles. But compared to other PCC's, a 5.7x28 PS90 gives you the reduced risk through walls that 5.56 offers. The only other downside is price.
Note that I don't think 5.7x28 compares favorably to 5.56 when you keep things apples to apples, though. I would not opt for a 5.7x28 AR. The compact design of the PS90 is a huge advantage in its favor.
And before the argument of "but handgun rounds will be even more powerful when shot from a longer barrel!" gets brought up, it isn't as simple as you think.
9mm and most pistol calibers actually perform worse in reality when shot from a longer barrel.
Yes, they get gains in velocity, often a few hundred fps.
But almost all hollow point loads are made for handguns with barrels between 3.5" and 5", for the hollow point cavity to expand at a specific rate to enable the projectile to reach a certain depth. Significantly increasing the velocity will lead to quicker expansion and thus shallower pe*******on.
I don't know of any 9mm hollow point loads that are designed to be fired from a 16" barrel and expand slower accordingly.
Also note that the velocity itself isn't increasing effectiveness. They aren't getting anywhere near the 2400-2500fps range required to produce so-called hydrostatic shock, so no, they aren't getting rifle-like wounding.
Anyway, when you stray from keeping it apples to apples, that's where some PCC's can shine. Some PCC's can be crazy affordable, like Hi-Point carbines. Some non-AR PCC's might be lighter weight than an AR. Some might be smaller. Some PCC's let you slap them like a ho**er. If your PCC is made to be slapped, then maybe that's a reason to choose that PCC instead of an AR, to exert your dominance over both man and machine.
