9mm vs 5.56 AR Pistol Build - UPDATE: 5.56 - Help me Build One!

[Emptymag]

I've been kicking around the idea of a AR pistol for a few years.
Back when the arm braces were the rage (before the "no shouldering" thing) I had intended to get one. I love me a short rifle and never met a carbine I didn't like, so the shorter the better - an AR "pistol" would be perfect. I thought it would make for a handy house gun as well. Then the whole ATF thing came about and money got harder to come by, and I just shelved the idea.

Well, now that I have 3/4 of the parts required to build a 9mm AR carbine, the thought occurred to me that since the 9mm isn't going to have the range of a 5.56 in a carbine, would it make any sense to build a 9mm as a pistol using a KAK Shockwave Blade instead of a carbine?

I know the "correct" answer is "build both" and that may eventually happen one day, but for now I'm just interested in the good and the bad for each.

Random thoughts/ponderings that may be helpful:

- In my novice mind, I tend to think that shorter barrels are better than longer ones (like 11") that don't really give you much more in the way of compactness than a carbine, so why bother doing a "pistol"?

- I have zero interest in a suppressor. None. At all. Not going to happen.

- I have zero interest in a SBR. Not going to happen. I can barely afford to buy parts one at a time, so I'm not spending more on stamps.

- Is it realistic to consider a 9mm AR pistol for home defense? Are there reliability issues that would make a 5.56 a better choice in that regard?

- I currently have two lowers on hand to work with. One is a standard Anderson stripped lower that was purchased that way - new/never used.
The other is a GWACS CAV-15 MKII lower. (obviously this can not be used for a pistol)
I started thinking that if a 5.56 would be a better choice for a pistol, I may use the CAV-15 lower for my 9mm carbine build instead of using the Anderson AR lower like I had originally planned and use the Anderson lower for a 5.56 pistol.
(is that too confusing?)

- I assume either caliber will be loud - very loud - in pistol length. I also assume the muzzle flash will be "harsh".
As I understand it, the shorter the barrel, the worse it is on both counts.
How do the 9mm vs 5.56 compare in this regard?

- I'm told 9mm has more felt recoil as it's a blowback design. My wife can shoot the 5.56 AR. Not sure more recoil would be desirable for her.
(on that note, shooting rifles/carbines is not easy for her due to back problems, so I wondered if a pistol AR may be easier for her to shoot if she so chooses)

- Money. I'm not made of it - keep the suggestions realistic from a financial standpoint.


Thoughts?


EDIT: See post #36 for update. I've decided to go 5.56 for a pistol.