When thinking of getting a 9mm AR I am hit in the face with the reality that an M1 Carbine may be a much better choice:

1. Firearm cost
9mm AR - $600 to $850 (kit only or whole gun)
M1Carbine - Commercial $300/USGI $450

2. Magazine cost
9mm AR - Mag Block + 10 used stens + loader is about $110
M1Carbine - 10 used 30's is about $110

3. Ammo
9mm is 1200 fps/380 muzzle energy
.30 is 2000fps/800 muzzle energy

4.Ammo cost
decent 9mm is $115 per case
.30 is $150

5. Preban status
Collapsible 9mm needs an $800 lower.
Collapsible M1 needs a $150 USGI stock

6. Scope mounting
Edge to the AR unless there is something I don't know

7. Accuracy is pretty much equal to 150 yards.

8. 9mm has edge in ammo selection unless you handload.

So I gotta know - Why would anyone take the AR 9mm over an M1? For me it just doesn't add up.

This is prett subjective ground.

Here's why I don't think an M1 Carbine is better.

1.  Commercial carbines generally have cast receivers.  None for me, Thanks.
2.  30 round non-GI carbine mags generally suck.
3.  I already have an M16, so a 9mm upper is just that much more fun.
4.  No good scope mounts.
5.  Trimming .30 Carbine brass sucks.
6.  GI barrels are getting scarce, especially if you have an M2 and actually shoot it regularly.


Here's what would make a .30 carbine more desireable than a 9mm AR.
1.  $1900-$2300 registered trigger pack for full auto vs. $5000+ for RDIAS.
2.  Like you said, cheap mags but non-GI 30 rounders generally suck.
3.  One-off factor.  Everyone has an AR.
4.  Correct refinishing is pretty cheap.  I know of two shops that do it for $120.

Edited to Add:

If I had $800, no guns and could only buy one rifle I'd think real hard about getting a GI M1 Carbine.
I recently had a new Sprinfield Armory receiver built up with GI parts as a host for an M2 parts set.  It was an accurate, reliable little rifle.  I could go to Wal-Mart and get ammo and once I got the right front sight on it, I didn't have to screw with it.
With the 15 round mags it went 'bang' every time I pulled the trigger.  It was much lighter and handier than a post-ban light weight AR with a notCollapsable stock.

In my case I just wanted a round I could use at the local indoor range and still shoot my AR. I already own a couple of AR's so all I needed was the upper ($381 shipped) the mag-block and some mags. I also have a 22 rimfire upper for cheaper-than-dirt plinken.

Quoted: In my case I just wanted a round I could use at the local indoor range and still shoot my AR. I already own a couple of AR's so all I needed was the upper ($381 shipped) the mag-block and some mags. I also have a 22 rimfire upper for cheaper-than-dirt plinken.

I know of no range in my area, indoor or outdoor, that prohibits any rifle caliber, including the .30 carbine.

depends on what you are going to use it for. to make noise and put holes in paper get a hi point.  for a house gun get the ar set up but in 10mm. the 9mm just pisses people off, and the 30cal carbine pisses of north koreans.

LarryG,
   The local indoor ranges here only allow pistol calibers and no steel jacket ammo like in some military stuff. These ranges are only 25 yards, great for pistols, sort of great for my 9mm but when I get a weekend off I go to the outdoor range and shoot the 5.56mm. I owned an M1 carbine years ago and now wish I didn't sell it but I needed the cash. I think the thing about 9mm (for me) is having it in an AR. I think it's more the rifle than the round. I can change around from 9mm to 5.56mm to 22 rimfire if I want.

Basically the same rifle system, so the body mechanics/familiarity of the weapon is the same.

Plus,  that whole .30 carbine thing is played out! (Kinda like Harleys).

I've shot M1 carbines and like them well enough, but I *own* a 9mm AR. My reasons were simple and worked for me; yours may vary. Bottom line is, to each their own!

1) I own other .223 AR's, and many parts are common to them and the 9mm carbine. Less for me to have on hand.

2) Ergonomics, sights and manual of arms are similar to my .223 rifles, simplifying training.

3) I own 9mm pistols and reload that caliber. .30 carbine would mean yet another caliber to buy or load for.

4) The indoor range where I shoot does not allow .30 carbine or any rifle round.

5) Blast and flash of the 9mm is less than .30 carbine; important if the gun is used as an indoor defensive weapon.

6) Ammo selection in 9mm is MUCH wider than .30 carbine, especially in defensive-type (hollowpoint) loads. Cheaper too!

7) Lots more widgets and gizmos available for AR-type rifles than for M1 carbines (grips, sights, stocks, slings, accessory mounts, etc).

8) AR is a modular system. In a pinch, I can pull off my 9mm upper, drive out the pins holding the mag block in place, throw on any of my other uppers and be shooting .223.

Just as a reference point, 556fiend, your M1 Carbine prices are on the low side by quite a bit! The IAI reproductions (good guns, BTW, and USGI-compatible) run about $450 new, while a genuine WWII carbine in good shape will set you back $550-plus. Any carbine you can find for $300 will probably be a Universal, which are for the most part garbage.

Assuming you already have an AR, otherwise that is what you should buy first.

I have an M1A1 (the paratrooper version).  I decided to sell it over a year ago, I just have been busy.  Carbine prices have gone up in recent years.  I will use the money to get a pistol caliber AR upper or maybe the USC conversion Cav arms is working on. I love .45's.

My carbine is as good as it gets. Folding stock, plenty of original GI mags, bayo lug, removable flash hider, light weight, compact, goes bang, light recoil, I have extra parts too.  I love it.

9mm versus 30 carbine.

9mm killed plenty of people in WWII, ask any Nazi.  No comparison in ammo choice.  Plenty of cheap 9mm for plinking, lots of good hot stuff for self defense.  Reloading selection is great for 9mm.  9mm is also a better cost value.  9mm is by far a better defense load.

M1A1 versus a Ruger 10/22 with folding stock.

Ruger is lighter, smaller, more compact, more main stream in terms of parts or ammo.  Packs even better in a canoe or pack than an M1A1.  Ammo is lighter.  Tons of parts and accessories available.  Can be silenced.  Can be used for hunting small game. more accurate at ranges to 50 yards.  Plenty of ammo choices.

I would never choose to defend myself with my 30 carbine over other guns I own.  Mainly because of caliber performance.

A folding 10/22 or AR 7 survival rifle packs better than a 30 carbine.

No matter what the carbine does, something else out there does it better for the same price.  It is a total compromise.  It was designed as a compromise from day one.