I already have a dedicated .22 AR style gun (M&P 15-22) and my 5.56. I'm going to be picking up a stripper lower soon and am debating on whether or not to build another 5.56 or assemble a 9mm. I'd like to go with a 9 since I also have a P226 and plenty of ammo. After reading through several pages here, I still have a couple of questions.

1. Are the 9mm builds as reliable as others? Seems that there can be finicky if you have a block that doesn't fit or different mags?

2. Are there any really good complete kits with everything you need to bolt to a lower?

3. Why do most that I see seem to be SBRs? Are there many 16" out there or a reason not to go that way?

RMW Extreme is working on a DI Model. See the last caliber note.
When it's available it'll totally Kick Butt. Ron Field Tests all uppers
before they ship. I have several of his 45 acp's and a 45 Win Mag.

http://www.rmwxtreme.com/

Dave S

Once you get it tuned, it will run like a clock. You should note though that some setups are less tolerant of changes than others. My RRA carbine runs fine with any ammo I've tried except aluminum Blazers, and I have it tweaked to run well with the Rock River modified Uzi mags I got with it, Metalform mags and even my CProducts magazines. My SBR works just as well within those same parameters. The tuning will involve a couple of things: making sure your ejector is aligned right, making sure your magazine block is placed correctly, and making sure your buffer and spring are appropriate for the ammo you're shooting. For example, my factory RRA carbine has their 9mm buffer (which is heavier than a carbine buffer) but my SBR runs 115gr and 124gr loads just fine with a standard carbine buffer. If you go with a "9mm lower" with an integral adapter, you may have less flexibility with different magazines - or not. It takes a little experimentation.

Good luck! I'm looking forward to seeing pictures of your build!

I have a 9mm AR pistol (until the stamp comes back) built with a CMMG 9mm dedicated lower and RAA upper with a 5" ADCO barrel, CMMG BCG, and Spike's BAR 7" handguard. It runs like a top and is a lot of fun (it will be more fun when I can put a stock on it). I also have a 16" Colt AR6450 9mm. It also runs like a top, but the 16" carbine just isn't as fun as the little 9mm guns. I think one of the great things about the 9mm AR platform is the ability to suppress it and get nearly movie quiet (my 9mm suppressor is pending also). Hanging a suppressor on already 16" gun just makes it too big IMO.

I had a Hahn dedicated mag block in a regular lower for a while, but I could never get it to run as well as the CMMG dedicated lower or the Colt. If you are serious about building a 9mm, get a dedicated lower. It isn't like the mag block is something you will be banging in and out on the range to switch uppers, and in my experience the dedicated 9mm lowers are much more reliable.

My 9mm AR took some initial tweaking. I got a deal on a bunch of c-products mags. The followers all required modification to work with my Hahn dedicated block. I had to send some of the mags back for replacement…

The ejector also needed to be properly aligned.

Now with Metalform mags and decent ammo, it runs great.

I have a 14.5 inch CMMG upper half with permanent flash hider to keep it non NFA…

People have mixed experiences with 9mm AR's. Some will swear they won't work right with anything but Metalform mags. I can not confirm or deny that statement as I have NEVER used a Metalform magazine in either of my 9mm AR's. I use three different magazine brands and don't have any issues with any of them. (CProducts, ProMag, and modified surplus military mags of unknown origin...Uzi or something)

When I built my first 9mm AR I used a RRA bottom loading magwell adapter. It took me two or three trips to the range to figure out just how to adjust it. Since learning the ins and outs of magwell adjustments I have had no further issues at all, even when I switched my magwell over to another rifle. Oddly enough using the RRA adapter in an RRA rifle gave me the most problems! I put the adapter in a Cav Arms lower and it was 100% from the first outing.

My other 9mm uses a CMMG dedicated lower. Its been just perfect from the fist, never one moment of drama with that one.

So, while some report all sorts of issues with various set-ups I have to say that my two 9mm AR's just hum along with my mixed box of magazines. Someday I might even buy a Metalform mag just to see what one looks like. I have seen pictures however. When my CProducts and ProMags wear out maybe I will try the "other brand". Meanwhile I think I shoot my 9mm AR less than my .22 AR but more than my 5.56mm (I reload and 9mm is so much faster and easier than 5.56)

Mine is finally running right but it doesn't like the plastic promags. It runs colt and converted Uzi mags no problem. I can't remember if I have used the Cproduct mag yet.

With good magazines and a good lower...yes. I have a RRA dedicated magwell rifle that I SBR'd to a 7" with a RRA barrel. Using RRA modified Uzi and CProducts magazines...I've yet to have a problem. Most issues folks have with the 9mm can be directly traced to magazines and the magwell block. I waited until RRA came out with their dedicated magwell lower before taking the plunge into the 9mm world. I don't like tinkering with my guns to get them to work and the various blocks on the market all have to be played with to find the "sweet spot". The newer lowers by DDLES, Lone Wolf, RRA and CMMG take all the guesswork outta the system. Stick with Metalform magazines and a quality lower and you should have no problems whatsoever.

AIM 9mm upper, Spikes mag block, Spikes 9mm buffer, converted Uzi mags. Once I broke it in and got the mag set up, no issues at all, and fast becoming my favorite AR. I do reload for it, and load a bit hotter just to make sure everything runs well.

A 16" 9mm AR kicks serious butt. It is a blast to shoot and is very controlsble. A 10.5" 9mm AR is a different kind of blast to shoot; still very controllable, still very cool, but different. The beauty of the 9mm setup is that it runs well in both barrel lengths with standard ammunition, and once you get the gun running, it runs like a top.

While I started out with a 16" carbine, I also built my SBR as a 9 (probably going to get a 11.5" 5.56 upper by the end of the year), and they both still rock. There are places that don't allow NFA weapons of any kind, and others that have special fees and limitations, so having both (the ARFCOM way!) gives me flexibility, I'm looking forward to seeing how both like cast bullets later in the year. Should be a blast.