Re: 9mm AR-15 Build- Need some info
Build vs. Buy is always a tough call and it really comes down to what you want/need/etc., how much you want to pay, and how long you want to wait (9mm AR parts can take a little while unless you find them in stock somewhere).
Several places offer complete 9mm uppers, including RRA, CMMG, Spike's Tactical, etc. Prices for complete, 16" barreled uppers (with bolt/carrier/CH) range from around $425 for the RRA units up depending on mfg, configuration, etc. The downside to the inexpensive RRA units is that they come with a non-ramped bolt carrier which necessitates use of the 9mm specific hammer which is yet another "non-standard" part that you have to worry about having a backup for, etc. If you go with something like the CMMG 9mm upper, it comes loaded with a ramped carrier which will allow you to use any standard AR-15 hammer (including some of the 1pc trigger units like the Timney, Wilson TTU, etc.), but drives the cost up to nearly $600 for the complete upper (but for that price, you get the ramped carrier, a WASP/nitrded finish, a 32rnd Colt/Metalform 9mm mag with LRBHO...a $40+ value, etc.).
When using a standard AR-15 upper on a 9mm build, you'll also want to pick up a dedicated 9mm ejection port door and brass/gas deflector. As for parts including barrels, etc., check with Spikes, CMMG, RRA, ASA, Rainier Arms, etc.
Once you decide on a whether to buy/build your upper, you have to select a 9mm mag block for your lower. There are dozens of different options, but personally, I would stick with the Hahn Precision Dedicated Adapter (if this is a dedicated 9mm build and you won't be switching back/forth between calibers) or the Spike’s Tactical Enhanced Block (excellent product, completely adjustable for fit/function, and easily removed for caliber changes). You will also need a specific 9mm buffer, buffer spacer (maybe), and recoil spring. I used a Spike’s Tactical ST-T2 buffer along with their buffer spacer (to shorten the stroke when using an AR-15 length buffer instead of the longer 9mm buffer) and I went with a Wolff AR-15 Carbine Extra Power recoil spring. I have also used Spike's dedicated 9mm buffer with good results along with the XP spring. Finally, I have also run one of Slash's (Clint Butler's) XH 9mm buffers which is excellent, but expensive compared to other options like the Spike's setup at roughly 2-3x the price).
Finally, as a word of caution...9mm AR mags are NOT created equal. You may get decent service from converted Uzi mags, the C-Products knock-offs, the crap-tastic Promag polymer mags...BUT at the end of the day, the OEM Colt/Metalform magazines are the only 100% functional/reliable mags with a LRBHO that I have found to date across a wide range of 9mm ARs from my own builds to factory RRA rifles to the original Colts. They are expensive at roughly $40/mag, but a small price to pay for utterly reliable function.
I don't have any pics of my last 9mm build with me here at work, but I'll try to drag some up when I get home tonight, as well as the build/parts sheet detailing the specifics of the build.
