For use inside a building...

[Girodin]

The advantages of the 9mm carbine as I see them are:
Shorter weapon.
Adequate terminal performance.
Less flash and noise, though still admitted too much.

I don't know that a 9x19 carbine is per se shorter than a carbine in 5.56, 300 BLK, 7.62x39, etc. Really you need to compare specific weapons. My Aug is shorter than some PCCs I have. My sub 2000 (which I wouldn't use as a primary defensive weapon BTW) is shorter than my 16" ARs. My SBR AK is very small and MUCH smaller than say a beretta storm with a 16" barrel. Obviously some of these comparisons are apples to oranges, which is my exact point. Caliber isn't nearly as determinative of length as other factors.

If you compare similar configuration guns a 9x19 may or may not be slightly shorter. An MP5 for example is (in similar configuration) basically the same size as an HK 53.

View attachment 712238

A 9mm Tavor is the same size as a 5.56 tavor. In an AR platform given similar barrel lengths the 9x19 is going to be the same size as an intermediate rifle caliber. I would be willing to go with a shorter barrel in 9x19 than I would in 5.56 or even 300 BLK (or 7.62x39). In 5.56 a 10.5" is as short as I would go and you do pay a penalty in terms of blast and noise. At CQB ranges and with out constraints on ammo selection any velocity loss is not terribly disconcerting. With a 300 Blk I'd use a 8" gun without much concern. In fact for use inside of 200 yards being shorter and having good terminal ballistics is one reason to pick a 300 BLK over 5.56. I've heard of people going as short as 6" on a 300 blk but have no experience and thus can't comment. I've used a 7.5" x39 and it has a lot of flash with the ammo I've used. [As an aside, for all the discussion of caliber no one has pointed out that ammo makes a huge difference in how much flash you get. Load selection can dramatically alter the amount of flash be it from a handgun, PCC, intermediate caliber rifle, or a 308. This point hit home in a low light class I did with various ammo in the same caliber being used.] With a 9x19 you can use even a 5" barrel. In fact for a gun that will have a suppressor you can wind up with something the length of a similar gun with a 12" barrel.

For all the back and forth and frankly uninformed noise, red hearings and straw men in this thread I think it has multiple times been boiled down to the right question:

"Do the advantages a pistol caliber offer make up for the ballistic disadvantage?"

In answering the question I think it is helpful to know if SBRs and Suppressors are one the table. Whether SBRs and suppressors is on the table changes the discussion a lot IMHO.

I also think it is useful to discuss the actual weapon type one is considering.

 

[RustyShackelford]

Uninformed, red herrings & strawmen....

Uninformed?
Red herrings?
Noise?
Strawmen?

Let's keep it classy San Diego.
Everyone can have a opine here, even if they are wrong.

RS

 

[barnbwt]

I wouldn't put up an MP5 as the best example of a compact PCC, they are probably one of the larger/heavier ones, truth be told (though great weapons otherwise). There is plenty of overlap, though. But just how effective is a 7" AR ballistically, anyway? It's not like it's the same round as from a much larger 16" barrel. Couple that velocity loss with the fact that PCCs don't really suffer from shorter barrels (not like rifles, at least) and the two platforms become even more similar in terminal effect.

So your flash/boom and possibly recoil due to lower weight go up, and your ballistic edge over PCCs narrows when the barrels get real short. Which is why PCCs are better compact weapons. But if we limit the discussion to what the NFA favors, of course full size rifle 'win,' because a rifle scaled properly for best design with a PC round would come out a short barrel. It's kind of a self fulfilling condition; the NFA was made to stop compact guns from being made, so you end up with an artificial lower barrier on rifle size that scales with a certain size of cartridge for best efficiency.

A B&T TP9 PDW is much smaller than an MP5, and way littler than the smallest AR.

TCB

 

[Girodin]

But just how effective is a 7" AR ballistically, anyway?

Chambered in what cartridge?

In 5.56 the conventional wisdom is that 7.5" guns are too short. They lose a lot of velocity and are very loud and have a lot of blast. Also they tend to be more finicky than 10.5" guns. Some chrono results I've seen have shown as much 500-600 FPS loss between a 16" barrel and a 7.5" with the same load. Many suppressors are not warrantied on 7.5" guns. Outside of certain niche roles I think I'd likely rather have a 9x19 than a 5.56 7" gun. For 5.56 I'd stay with a 10.5" gun at the shortest.

That said there are other cartridges that do better in short barrels. 300 Blk and 7.62x39 for example. My 7.5" x39 was showing around 2000 FPS the last time I chronoed it with 123 grain wolf ammo (which is not a particularly hot load.) My 11.5" AK only loses about 200 FPS versus a 16 gun. If I wanted to run a really short AR it would be in 300 Blk. I haven't chronoed an 8.5" black personally but the numbers I've seen suggest relatively little velocity loss between even an 8.5" and 16" gun. 8.5" 300 BLKs don't seem to be nearly as objectionable as 7.5" 5.56s in terms of flash and blast either. I see people reporting 2100 FPS with 125 grain bullets. I don't get that with my 16" 9x19 guns. With 115 grain +p loads and 16 barrel you are looking at around 1600 FPS.

Of course energy numbers alone do not tell the story of terminal ballistics you also have to account for bullet design and construction.

A B&T TP9 PDW is much smaller than an MP5, and way littler than the smallest AR.

The civilian version of the TP9 that DSA was the distributor for also had a ho hum trigger , a lot of gas blow back out of the port when suppressed, horrible ergos, and uncomfortable stock. Oh the irons were also pretty crappy, but mounting a RDS is not an issue. It is very compact but I would much rather have an MP5 or a 9mm AR for a gun fight. Small might be better for some uses but is not necessarily the summum bonum for all uses.

 

[barnbwt]

I was speaking to its size, not its practicality (I don't think I'd use something that rare for HD, anyway). The more important issue, is that the TP9 would have to be in pistol configuration with no stock unless it is made an SBR --once again an example of how the NFA arbitrarily sets an artificial lower limit on how small we can make a pistol caliber carbine; that lower limit basically being a full size rifle about the size of the AR (since a 223 is about the right size of cartridge needed for a full 16" barrel, whereas a 9mm is comically overbore at that point). The purpose of the SBR statute was to prevent civvies from getting concealable rifles; otherwise known as compact rifles

The SIG MPX is also significantly smaller, although its heavy reliance on AR components and layout negates a good portion of this, it's still shorter & lighter.

The reason why I keep harping on the size/weight angle, is because they are the only real advantages over a larger gun. If your personal experience leads you to believe pistol rounds are sufficiently effective against an expected type of foe, there is no reason to make the gun/cartridge larger than necessary (unless, of course, you happen to simply like/shoot the larger gun better --same as pistol rules). A powerful round can leave a wide wound track, but it still seems like there is way too much unknown about that effect* to rely upon it, which means you'd still have to be as accurate with whatever round you choose to ensure effectiveness.

TCB

*Only if you know exactly how much wider the wound path is from pistol cartridge's, can you make the claim that you can be X amount less accurate and not suffer a disadvantage. And even then you'd have to practice with both rifle and pistol guns to determine if you meet/surpass that threshold to justify the more powerful gun.

 

[Balrog]

Without delving into Class III/SBR's, the Beretta Storm Carbine is lighter and shorter than a non SBR AR.

 

[strambo]

I didn't delve into SBR/non-SBR, can, no can etc. too much as applied apples to apples to each, the PCC will still come out shorter, lighter and quieter generally speaking.

I do see the Storm carbine is 5.7 lbs unloaded. Getting a bare non-SBR AR at 6lbs isn't too difficult with a LW barrel, and one of the new very light rails (KMR and similar). It will be longer than 29.7" though, but a lightweight permed 14.5" AR would give it a run for its money in overall handling.

I look at a firearm for its strengths and weaknesses and seek to maintain the strong points while minimizing the weak ones through hardware and/or training.

We all seem to agree the PCC/SMG is lighter, smaller, weighs less, has less blast, recoil, noise and flash in comparison to a rifle carbine. Its biggest weakness is the handgun chambering offering weak terminal effectiveness.

You can maintain the PCC's strengths by keeping all the tacticool crap off it, adding only a micro dot, small light, and sling. You can't make it more powerful though, all you can do is try to place shots better, but isn't every shooter doing that to the best of their ability? The fast handling and low recoil will help follow on shots be quicker and closer in general which will help with placement so that is a plus.

The rifle chambered carbine has the mirror image strength/weakness list. However, unlike the PCC where there isn't anything we can do directly to improve the main weakness; less terminal performance, we can really attack the list for the rifle carbine.

We can use LW components, we can use a great flash hider, we can use midlength gas and an A5 recoil system, we can SBR it, put a can on it, or put on electronic hearing pro and train proper shooting position with it. This and more will narrow the gap significantly with the PCC on its weak points all while keeping its biggest strength.

Of course we can do all those things to a PCC as well and get a really light/handy weapon, but that won't do anything to address its biggest shortcoming and it was already light and fast handling.

I know someone will mention how much that will cost, but the thread is about which is superior not which is the best on a subjective cost basis. Plus, a lightweight permed 14.5" AR off the shelf and a pair of electronic hearing pro on the nightstand would an extremely effective and low cost HD option.

A well-trained shooter can run a typical AR at 5 yds on multiple target so fast is sounds almost like a machine gun. From a hardware perspective in terms of real-world performance, it gives up very little in handling to a PCC while offering a lot more terminal effectiveness with every shot. That an individual may be lesser trained, not as strong, or just more familiar/better able to use a PCC than an AR doesn't make the PCC as a class superior for use inside a structure. That is an individual issue and/or software issue, not a hardware one.

Put another way, if someone is good enough to place shots with a PCC fast and effectively in a gunfight, they would also be able to do so with a sensibly set up 5.56 AR. Another poster put up percentages. The first round time is the same, I'll take a 10-15% increase in splits and transitions for the drastically increased volume of tissue damaged per round. 15% added to a .25 split is .2875. 10% on a half-second transition is .55 sec. and the first rifle round has slammed into them already.

 

[Balrog]

We all seem to agree the PCC/SMG is lighter, smaller, weighs less, has less blast, recoil, noise and flash in comparison to a rifle carbine. Its biggest weakness is the handgun chambering offering weak terminal effectiveness.

I guess the only real disagreement we have is that you say the PCC has "weak" terminal performance. I think it would be better to say "weaker" terminal performance than a 5.56 carbine, but I am not sure that calling it just "weak" is valid. I think you can get near 357 magnum velocities with the right 9mm loads and a carbine barrel, and I don't call the 357 weak.

 

[barnbwt]

Is it just me, or does it sound like we're trying to adapt both platforms into the same animal somewhere in the middle; milking as much as we can from the PCC ammo with +P and expanding rounds, sacrificing some of the power of a rifle with short barrels to get a smaller size, seeking to reduce the effect of its extra power with muzzle devices, and working to reduce its length of pull and weight as much as possible (or bullpupping the design)

I don't suppose you'd also think a hot 10mm or 357 class round would achieve both fully adequate terminal effect while maintaining a significantly smaller/lighter platform. I've said for a while that there is a gaping hole in the gun continuum, between rifle and subgun, that continually persists because an idealized gun there would cost as much as a rifle, but be less commercially marketable due to "bigger gun for the buck" syndrome.

TCB

 

[strambo]

I think of it as almost binary. At handgun velocities (any velocity below ~1800-2000 fps) all you get is a hole for tissue damage.

At rifle velocities (2000 fps and above) you get both the hole damaging tissue and tissue damage in the temporary stretch cavity. This is a massive increase in wound volume resulting in a massive increase in blood loss resulting in a lower time to incapacitation.

It isn't truly binary as it is a velocity range that some PCCs can approach (lever action 357s for sure, not auto pistol rounds) and tissue damage in the TC is greatly affected by bullet design. Pointed spitzers at rifle velocities don't upset and tear nearly as much tissue in the TC as an expanding soft point, a round that fragments, or a flat point would.

As relatively "powerful" as a 9mm clocking 1600 fps is compared to typical handgun rounds, it is still just gonna punch a hole the size it expands to. The chief ballistic benefit to a non-SBR PCC is the added velocity paired with the right bullet can make sure you get good expansion and more penetration than from a handgun barrel. I have seen a lot of handgun bullet tests where a bullet does well from the handgun and poorly from a carbine though, they (modern HPs) are designed to perform in a velocity envelope.

 

[CraigC]

At handgun velocities (any velocity below ~1800-2000 fps) all you get is a hole for tissue damage.

What is this based upon?

 

[Balrog]

What is this based upon?

At typical handgun velocity, there is not enough energy associated with the protective to cause death of tissue adjacent to the bullet tract.

I have operated on people shot with handgun rounds and rifle rounds... Rifle rounds cause death of tissue around the bullet tract, but handguns don't.

 

[CraigC]

No one is arguing that rifles don't do more damage. However, to say that with a pistol cartridge, all you get is a hole, is a wee bit misleading. I'm about to start testing the 150gr Cutting Edge Raptor in the .38-40 and expect to see a lot more than "just a hole". Ever seen a lacerated heart that was adjacent to the bullet's path? I have. Ever see an LBT blow through making a mess akin to a rifle cartridge? I have.

 

[Steel Horse Rider]

Given the information given this last page I would like a clarification of what the purpose of this post was about. Was it to determine something, a platform for a pointless argument, or to determine what to purchase for home defense?

I don't know why I keep checking on this thread other than the lure of watching a train wreck occurring within view. My lone contribution was from my nephew's first hand experiences as a Special Forces Operator picking up "people of interest" in Africa, Afghanistan, and Iraq. Special Forces guys are trained to shoot in the head, which I think is the proper training target for those interested in home defense. If you are confronted with a home defense situation I think most folks would be perfectly happy with whatever weapon they are proficient with and is LOADED and close at hand. I believe the quicksand of trauma, noise, muzzle blast, and the other "what if" scenario's that have been presented in this discourse have little bearing on the outcome if the target is the center of the forehead and is hit with any moderate to high velocity projectile. The only surgery that may be relevant will be in conjunction with an autopsy.

 

[12Pump]

Personally, I would think the muzzle blast is something to be concerned about, especially indoors. Fire one shot of something with severe blast, and it could really disorientate you. That's why police throw flash-bang grenades into our homes when they do raids. They want to disorientate the occupants first. I wouldn't want my own gun doing that to me. Yes, I'm aware that any firearm fired inside a home without hearing protection will cause hearing damage. But some will be less painful and disorientating than others.

 

[Zerodefect]

Just test them. And test your muzzle devices accordingly.

The subsonic .300BLK is still more powerful a 9mm PCC out of a pistol AR or SBR AR15. Less flash and noise as well. Lower output 6.8SPC is available as well. There are other options.

IMO, those two rounds are more reliable than pistol round magazines in an AR.

Nothing wrong with a FN P90 or Beretta PX4.

 

[ugaarguy]

After 6 pages we're running in circles and all the arguments for each side have been stated, restated, rephrased and stated again. Let's quit chasing our tails on this one.