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

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? :confused:


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

I, the same as you, went through this thought process recently and I chose the longer 10.5" 5.56 over the 9mm. I dream of making a 9mm ar that takes Glock mags and the new psa lowers look pretty good.
I chose to build in 5.56 because I found the upper with bcg and ch for a good price and I couldn't help but finish the build.
I think a Glock magged shorter barreled pistol make more sense for HD because the flames out of the 5.56 are ridiculous.

I never shot an Ar pistol that had a brace on it... but with out any kind of brace they seem awkward TO me

I had a 9mm and 5.56 pistol, IMO both are a waste without a stock. If it were me since a SBR is not in your plans, I'd build a carbine.

As for the recoil difference, the 9mm has a different feel due to blowback and it has less recoil than a 5.56, unless you set up your 5.56 with an adjustable gas block and brake, you can virtually eliminate muzzle rise and keep felt recoil to a minimum.

Quote:

---

Originally Posted by smoke-wagon

I, the same as you, went through this thought process recently and I chose the longer 10.5" 5.56 over the 9mm. I dream of making a 9mm ar that takes Glock mags and the new psa lowers look pretty good.
I chose to build in 5.56 because I found the upper with bcg and ch for a good price and I couldn't help but finish the build.
I think a Glock magged shorter barreled pistol make more sense for HD because the flames out of the 5.56 are ridiculous.

---

I already have a 9mm mag block insert for Colt style 9mm mags. (and a handful of 32 rd mags)
If I didn't already have the lower I wouldn't have gotten the mag block - I'd have gotten a Glock mag lower. (I have a G19 and a handful of 33 rd Glock mags)

Maybe once I decide which way I'm going with the 9mm build, I'll do the other version using a Glock mag lower sometime down the road?
I was all set to finish this carbine build once I pick up some extra work and all of a sudden I got it in my head to consider a pistol build.

Yeah, huge fireballs are not really desired, so that's why I figured I'd ask for some info from those who have them.

Can't really see the benefit of any pistol caliber SBR/AR pistol to be honest.

Yeah the 5.56 loses a lot of energy coming out of such a short barrel but it's still more powerful than a 9mm round.

I guess the biggest thing is ammo cost in the long run. I question cost savings since you can end up saving a lot on mags just sticking to 5.56 unless your AR pistol takes mags from a pistol you already own.

Other than ammo cost I don't see much of any other benefit of going with 9mm.

I've got an AK pistol that is 5.56 and I barely feel any real difference in felt recoil to my 16 inch AR-15.

http://i247.photobucket.com/albums/g...BBDBBA1E9B.png

There's my 10.5" with KAK micro flashcan

Quote:

---

Originally Posted by JDA58

I never shot an Ar pistol that had a brace on it... but with out any kind of brace they seem awkward TO me

---

That's why I mentioned having a brace. :cool:

Id prefer a 8-10" 9mm for home defense, 556 in a short barrel loses too much energy and gains too much flash/noise (and I like flash/noise) 9mm sha a sproingy feeling recoil kinda like an AR when comparing to an AK but even more springy.

Short barrel ars in 5.56 are ungodly loud. If you're going to use it indoors ever the flash can is a must. It's still going to ring your bell though.