9mm AR-15 - Good Idea or Bad?


January 10, 2009, 01:23 AM
the title pretty much says it all - what's the popular opinion on the AR-15 chambered in 9mm?

seems like it might be a fun firearm to have, shoots cheaper than the 5.56/.223. I also like that the majority of those I've seen are 1:10 twist, which I think would tumble the 9mm projectile in a way that would be seriously detrimental to the well-being of the target.

what do you guys think?

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chris in va
January 10, 2009, 02:47 AM
My CZ 75b has a 1:10 twist. I don't think it tumbles the bullet.

January 10, 2009, 06:47 AM
Generally speaking, a bad idea.

The reason it's a bad idea is that the AR was never meant to be a 9mm, and certainly not a blowback operation (or a piston either, for that matter). The 9mm guns beat up internal parts, can be finicky to get to run, and are magazine sensitive in many cases. The last is a bigger problem than it should be because CProducts has pretty much become the sole-source for 9mm AR magazines, and anything they're involved in is trouble.

But, I own two. :evil:

If you have a desire for a hearing safe suppressed AR, or a need for a training tool for indoor ranges, or want to attend subgun matches and not change your manual of arms very much, AND have the time to tinker if needed, the 9mm AR may work well for you.

I would advise going into the project with the expectation that you'll have to tinker with the magazine block, replace or modify some internal fire control parts, and perform surgery on any magazines you may buy. If you expect to have to do all of this, and you get lucky and the gun just runs with whatever magazines and whatever ammo you put in it, then you'll be pleasantly surprised. If you expect the gun to run right out of the box, and it doesn't, you'll be seriously disappointed.

January 10, 2009, 07:35 AM
I thought about this route and ended up getting a MP5K-PDW clone instead.

If you just plain want cheaper and the same platform, get a .22 upper.

Gary G23
January 10, 2009, 08:32 AM
It's just a ten pound pistol. I don't see the point.

January 10, 2009, 08:34 AM
I thought about it so I could shoot some local matches hat are pistol caliber only. After having seen many that required tweaking I bought s semi-auto Uzi, which I've been very happy with. BSW

January 10, 2009, 09:06 AM
AWESOME! (http://www.thehighroad.org/attachment.php?attachmentid=89343&d=1229352418) Tons of fun. Cheap to shoot. 100% reliable with the right ammo. (finicky with some I have tried) It does not tumble bullets. It is very accurate actually.

January 10, 2009, 11:39 AM
Instead of a 5.56 ,no.
The 9 has lots of good uses,for me it is a good thing because my club has a indoor range where the 9 is good and we can't use rifle caliber.
For the rest of you southern bums there are lots of us northern guys who do some of our shooting indoors for part of the year!

January 10, 2009, 12:20 PM
I would go with a .22 upper instead and switch between that and .223

January 10, 2009, 12:37 PM
I personally have little use for a pistol calibered rifle-- period.

What use it has for ME, a handgun will do in a smaller size.

I looked at getting a semiauto SBR Uzi a while back and then realized that I was just going to spend north of $1K for a heavy "handgun."

Now, if I was able to get one full-auto and suppressed, you better damned believe I could see how it would have a niche in my collection.

But that probably won't ever happen for me. If I was springing the money it would take to get a Class III AR lower, I wouldn't do it in 9mm.

-- John

January 10, 2009, 12:39 PM
My Olympic 9mm takes Glock mags. Hundreds of rounds and so far no failures.

January 10, 2009, 12:58 PM
Parts breakage usually results from an unramped bolt which transfers too much force from the bolt recoiling to the hammer pin (which usually snaps in two after a little while). Simple fix is to have the bolt properly ramped or keep a supply of hammer pins on hand.

Mag blocks - rather than a pinned-in set of Colt mag blocks, look for the removable VM-Hytec mag block. It accepts unmodified Uzi mags and comes out quickly and easily so you can revert back to 5.56 at any time. Colt mags are not great, but they do work (and occasionally 'volcano' rounds out the top of the mag). Using the VM-Hytec blocks allows you to use better, more robust and reliable Uzi mags, which are also much less expensive than Colts or even C-Products mags.

As to the claims its just a heavy handgun, I have to disagree and I've had several M16's in 9mm (two with 10" 635 uppers and a one with 7" 633 DOE upper). Even from a short barreled rifle, you get more velocity, longer sight radius, and a stock for more accuracy at longer ranges. Also, if you SBR the lower, you can use it in other calibers (.22LR, 5.56, 7.62x39, .45 ACP, etc)also; its not restricted to just 9mm.

January 10, 2009, 02:21 PM
I have an Olympic 9mm upper I use with a socom block and sten mags. It is a blast to shoot (really fun if you like bump firing). I used it in carbine steel plate matches and it works great. Out to 100 yards, no plate was safe. I fed it cases of Wolf 9mm when it was $80.00 per case, and I had no operational problems at all. It is, what it is. No need to compare it to everything else, or someones declared purpose. It can be for whatever purpose you want it for. Mine is for having fun, and it works well for that.

January 10, 2009, 02:22 PM
hmm...I was unaware of the seemingly frequent issues that some of you have had using a 9mm AR...oh, well - I really liked the idea, at least. I think I'll just buy a .22 LR upper for plinking fun.

one question - what's SBR? I see MGshaggy used that term in reference to a lower.

January 10, 2009, 02:24 PM
Short Barreled Rifle; a rifle with a barrel shorter than 16". Requires registration and a $200 tax to make or purchase.

January 10, 2009, 02:27 PM
The bolt ramping thing applies to the Colt and RRA guns. Not the olympics.

January 10, 2009, 02:33 PM
The bolt ramping thing applies to the Colt and RRA guns. Not the olympics.

True. I had an Oly, but didn't like the sten mag blocks it used or the wire ejector. The blocks had a lever on the bottom to release the mag, but if you forgot and hit the standard mag release button on the receiver, it would drop the mag and the blocks. Cost me a lot of time during a match - after that I went to Colts.

January 10, 2009, 02:41 PM
I've got the newer model that just takes Glock magazines. Of course the lower can't be used for anything else. It uses a mag catch in the normal place though.

January 10, 2009, 02:55 PM
ok, another question - where do you guys find .22 LR uppers/bbls? I checked all the major mfgr sites and cant find any...help?


January 10, 2009, 03:08 PM
where do you guys find .22 LR uppers/bbls


January 10, 2009, 03:16 PM
Strange all these comments that a 9mm carbine is just a heavy pistol. A 9mm carbine produces energy levels and penetration that are greater than just about every handgun out there.

Out of an AR it is a bit of a waste and as others have mentioned finicky to say the least. But a nice light Carbine such as a HiPoint or Marlin has it's uses.

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