For use inside a building...

Just my handful of pesos:

-the pistol round out of a carbine will have higher velocity, and the addition of the shoulder stock would make it more accurate, than the same round fired out of a pistol, BUT an actual rifle caliber is going to perform better.

- I'm not sure how it can be shorter than an AR, since federal law dictates a minimum barrel length of 18" and minimum overall length of 24" so unless you're willing and able to go through all the tax stamp hoops, you're limited by legislation as to how compact you can get the gun. Granted, a bull pup style weapon would be more compact than an AR, but they are still available in rifle cartridges (I'm actually unaware of any PCC bull pups, but if anyone has pics or experience with them, I'd love to see)

- rounds like 5.56 supposedly won't penetrate through drywall and interior walls as much, making it relatively safer than the PCC.

-you might be on to something with the lowered muzzle flash and sound of the PCC but I'm not knowledgable enough about that to comment on it. I think a suppressor would be an equalizer to that though.

Min barrel length = 16"

First, a pistol caliber carbine may not be quieter than a short barrel AR. ANY firearm going off inside a room or hall way will still exceed 125 db and that is going to damage hearing no matter what. It's not a given that a rifle round is noisier than a pistol.

Second, you can have a 10.5 barrel on a AR without a tax stamp. Buy or build an AR pistol in a rifle caliber ie, reverse the configuration in the OP. The significant difference is that it has no stock - but that is moot with the SIG brace and others coming on the market. Secondly - a lot a-s-s-u-m-e the rifle stock will be more accurate, but nobody goes to the extent to prove it. In a direct comparison the only difference would be the stock, all other parts would be identical. Meaning, pull off the stock and try it yourself, the BATF has no legal length definition of a pistol barrel. (BTW, the BATF does frown on trying to make a rifle into a pistol but if the lower was built as a pistol first it's entirely legal. Caveat emptor.)

What the SBR builders do is put together the entire gun sans stock (pistol!), file for the stamp, and then GO SHOOT IT as a pistol. They almost never to a man report the huge increase in accuracy when they legally attach the stock. What they do say is that it allows them to continue to practice - and that must be worth the ammo since we get no complaints about it being unable to hit the side of a barn without a stock.

So, no, it won't necessarily be any quieter, won't be shorter, won't be "more accurate" - we are talking distances measured in feet, not yards - won't have any quicker follow up shots, and won't be more effective.

Proof of concept is that most SERT teams carry a M4 type weapon in 5.56. Not 9mm. And the best way to emulate that in civilian mode - say, for HD - is the AR pistol with or without brace. It could be identical in every other aspect as the ones being carried by the guys coming to bail you out and arrest the home intruders.

Hey, maybe they would even give you a ride in the MRAV.

Balrog, I've often internally debated the PCC with less noise vs 5.56 AR (or other small rifle caliber carbine of your choice) with less penetration risk. For now, my solution is keeping valved ear plugs or electronic ear muffs close at hand with the 5.56 AR I already own.

kayak-man, 16" is the minimum bbl length on rifles. As far as pistol cal bulpups, I have no experience. However, Steyr does offer a 9mm conversion kit for the AUG, including the US built AUG A3 Semi-Auto. IWI is also selling the 9mm conversion kit for the Tavor here in the US. The Tavor kit even uses Colt SMG type mags. Unfortunately the Tavor 9mm kit will set you back nearly $800 on top of the price of the price of the rifle itself. Ouch.

That's right, it's 18" for shotguns, and 16" for rifles. Had a little brain fart

My nephew was in the Special Forces for 19 years, the last eight as an operator, and he used an M-4 and flash bang grenades for clearing buildings. He had his choice of weapons from pistols to AK's and chose the M-4 which tells me that it must be very useful for that purpose. He had a lot of experience clearing buildings so I would take his example over a collection of armchair quarterbacks.

m4 is short and compact,plus,if the situation changed where he might have to engage at a longer distance,he can.weapons/ammo compatebilty with rest of team

Noise issue aside for the moment I used to think that it was crazy to use a fast rifle round in a building situation. But then the physics of the round were explained. The small and light 5.56 is really moving fast. But at the same time it only takes a small mass to cause it to fragment and stop. So over penetration of walls and hitting anyone on the other side is reduced compared to a slower but much heavier PCC caliber bullet. So part of the reason for the switch away from PCC's like the MP5 to 5.56 arms is related to the need for avoiding excessive penetration.

There is still no real comparison between your typical pistol caliber rounds (speaking of guns best suited for defensive use) and guns chambered in 5.56 or 300 blk.

What the SBR builders do is put together the entire gun sans stock (pistol!), file for the stamp, and then GO SHOOT IT as a pistol. They almost never to a man report the huge increase in accuracy when they legally attach the stock. What they do say is that it allows them to continue to practice - and that must be worth the ammo since we get no complaints about it being unable to hit the side of a barn without a stock.

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To me there is a night and day difference between my SBRs and when they were pistols. Shoot any number of the common drills ins shot timer and tell me there is not. The arm brace can help narrow the gap but I'd much rather have a real stock based on my use of each. A lot of people own shot timers and this is not hard at all to quantify.

Something like an 8.5" 300 blk with a suppressor would be my choice over a 9x19. In 5.56 I don't like shorter than 10.5. A light weight BCM with a KMR and a can handles as well as many 16" guns I've handled.

Realistically one could be well served with either a ppc or a rifle caliber carbine. In absolute terms a properly set up rifle is in my opinion a better weapon. That's part I why the SMG has been falling out of fashion for CQB.

Get a quality weapon, get training, practice, and don't word about how many angels can dance on the head of a pin.

Balrog said:

I am not really thinking house clearing by Navy SEALS. I am thinking more along the lines of civilian home defense. The ability to engage targets beyond the effective range of a pistol caliber carbine would seem not to important to me in that situation.

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The closest thing I have to a pistol caliber carbine is my old Ruger 44 Carbine chambered in 44 Magnum. The tube magazine holds 4 but I can get 5 putting one in the chamber and adding one to the magazine. There are also a few AR types laying around.

My choice for home defense is one of my traditional 45 ACP guns in 1911. I can go 7+1 or 8+1 which for my purposes should be more than adequate. I know the width of the largest room in my home and I know what is beyond my home in any direction and for me the simple 1911 is what I see as my best choice.

As to noise? I do not keep hearing protection on my night stand. If God forbid I ever need to use a gun for home defense my last concern is the bang. Never wore hearing protection hunting?

Everyone's mileage will vary as I figure you choose a home defense gun based on your specific circumstances and I doubt we all have homes with identical floor plans.

Ron

A pistol caliber carbine is an SMG. You do not want to be shooting any firearm inside unless you absolutely must do so. One shot from a .22 CB cap will cause permanent hearing loss. A .45 or the like can actually hurt.
And there is no such thing as 'less flash' in dark conditions. Instant 'night vision' incapacitation with anything.
Home defense has nothing to do with hunting. You won't be hunting inside.

Balrog said:

So are you saying that it doesn't matter how loud the gun is, they will all cause hearing loss, so there is no difference in damage between a 22 LR and say a 30-06??
What if you are in dim but not dark conditions. Is there still no difference between a little flash and a lot of flash?

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I do not think anybody is saying that. When it comes to noise, any noise can cause NIHL (Noise Induced Hearing Loss) if the noise is loud enough.

Every day, we experience sound in our environment, such as the sounds from television and radio, household appliances, and traffic. Normally, these sounds are at safe levels that don’t damage our hearing. But sounds can be harmful when they are too loud, even for a brief time, or when they are both loud and long-lasting. These sounds can damage sensitive structures in the inner ear and cause noise-induced hearing loss (NIHL).

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So to cause damage the sounds must exceed a certain level. The louder the sound the greater the damage can be. So, yes, there is a difference between a 22 LR for example and a 30-06 rifle sound. There are no shortages of charts out there that define what sound levels are acceptable at at which sound levels damage begins to occur. Where would you place a firecracker (standard class C 1.5") with respect to a 22 LR standard velocity? CCI advertises their 22 LR Quiet at around 68 decibels at the shooters ear. Would that be a safe level without hearing protection?

Ron

I have a lightweight 13.7 barreled + Noveske KX3 flaming pig pinned on = 16". I use 55 grain ball in it with an Aimpoint Micro with the 4MOA dot for home defense. The flaming pig sound redirecter works very well for blowing the sound forward and when tunnel vision effect kicks in the auditory system changes. I have bad hearing I don't practice with out hearing protection but I have shot the thing a couple times with out any in a 12' x 20' room with an open door and it SEEMS less than a .357 mag revolver going off FWIW. My Calico 9mm carbine does seem a slight bit quieter but not much . I trust my M$ thingy.

If the possibility exists that you are going to be dead in a minute long term hearing damage is a moot point. How many home invasions do you think you will have to repel? My nephew always chuckled when he told us of the U.S. Army's plan to stop the SF members habit of using chewing tobacco due to the health hazards involved as if their regular day's work was not hazardous to their health both short and long term......

On the sound issue just test for yourself. Try the 9mm vs the 5.56 in guns of your choice both outside and inside. No hearing protection.

Then there are revolvers which are typically a lot louder than autos. Even a .22LR revolver can make some major noise.

Test for yourself. Don't take others' opinions as gospel, even though you asked for those opinions. It amazes me when people ask a question when they already have their mind made up. So go test for yourself and come back and tell us how your empirical study went.

The MP5 formula has been working for a long time; it still works, despite being supplanted by the AR carbines. The nature of a changing mission makes the AR the more versatile and effective choice.

I've fired my MP5, AR and AUG in a low-light indoor range, back to back, on the same day. There is no question that the decibels, muzzle flash and concussive blast of a 5.56 NATO are far more offensive, obnoxious and disorienting than a 9mm that is enjoying the benefits of a full powder burn.

In team use, which one do you want me to be firing one foot away from your head? If you don't think the 9mm is more mild, then you are kidding yourself.

How could one say, with a straight face, that the brightness of a muzzle flash, or the additional decibels are not any more harmful? If that were true, companies like Surefire and Streamlight wouldn't exist; nobody would need more than 10 lumens to blind and disorient the enemy. Nobody would bother with suppressed, supersonic applications; you're going to suffer the same degree of hearing damage anyways, right? Obviously neither of those statements carry over into reality.

On the sound issue just test for yourself. Try the 9mm vs the 5.56 in guns of your choice both outside and inside. No hearing protection.

Then there are revolvers which are typically a lot louder than autos. Even a .22LR revolver can make some major noise.

Test for yourself. Don't take others' opinions as gospel, even though you asked for those opinions. It amazes me when people ask a question when they already have their mind made up. So go test for yourself and come back and tell us how your empirical study went.

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ABSOLUTELY NOT! Telling someone to fire a gun with no hearing protection is dangerous and irresponsible. Further, without precise sound measuring equipment, the best that can be attained is subjective observation. It would in no way be empirical.

Balrog, you have nothing to apologize for. You asked a legitimate question seeking discussion on the pros and cons of 5.56 NATO (and implied similar high velocity intermediate rifle cartridges) carbines vs. pistol caliber carbines. Sound vs. penetration risks vs. terminal performance are all factors that should be considered when evaluating the choice of HD firearm.

i believe the full size rifle barrel comprised of 10.5 inch barrel with a 6 inch flash hider is the prefered thing because most people who advocate using that 223 for building work, always follow up with "get a suppressor"