9mm AR15 Build

giggitygiggity · Nov 12, 2011

When building a 9mm AR15 from a stripped lower, such as the Double Diamond lower, does the 9mm AR require different lower parts than the .223? From my understanding, the trigger, springs, pins, etc are all the same. However, the buffer tube, buffer, and spring are what concern me. Are these parts the same for 9mm as for .223? Does anyone have any advice on such a build? Thanks.

451 Detonics · Nov 12, 2011

I had an Oly factory built as a 9mm and it was totally problematic. On semi it was at best 80% reliable and in full auto i don't think I ever got through a full magazine. Sorta ruined me om 9mm AR tho I have seen builds that work.

When it comes to the buffer and spring I would use a purpose made buffer such as this one from Rainier Arms...the .223 spring should be fine.

http://www.rainierarms.com/?page=shop/detail&product_id=85

good article here http://ninthstage.com/index.php/2006/03/02/build-your-own-9mm-ar-15-lower/

Jon_L · Nov 12, 2011

Depending on the bolt, you may need a 9mm hammer--if the bolt is ramped, a standard AR LPK will work; if it isn't ramped (and they will say if it is), you will need a 9mm hammer. I've heard of people using a 5.56/.223 buffer in 9mm set-ups all the time without issue, anyone else?

BTW, how sweet is the new DDLES lower?

Walkalong · Nov 12, 2011

However, the buffer tube, buffer, and spring are what concern me

The buffer is different. I use a heavier buffer with a spacer in the back side of my buffer tube to keep the buffer from getting a running start when it hits the bolt catch. There is a longer 9MM only buffer. This keeps it from breaking bolt catches. Some hammers will not work as well. A standard DPMS style hammer will work. The RRA two stage match hammer can lock the gun up tight as a drum. A ramped bolt is a good thing as well.

Captain33036 · Nov 13, 2011

My 9mm AR build has a Bushmaster standard lower. I replaced the standard buffer with a 9mm buffer. No spacer and used the same spring. Works 100%.

The most important part of an 9mm AR build is the magwell block. The advice I have gotten from everyone is to go with either a Hahn dedicated or Spikes. I have a Hahn dedicated and it has never failed.

Do not know much about the 9mm bolt and hammer...except that you should have a ramped 9mm bolt. My CMMG upper came with that and it has worked perfectly with my Bushmaster standard trigger.

Hope this helps

Best

J

Taurus44 · Nov 13, 2011

With a ramped bolt, you can use any regular LPK. I'm not sure anyone is even making a 9mm bolt that is NOT ramped these days.

As for the buffer, you can use a regular carbine buffer, but most use a heaver (H1/2/3) one. I am running Slash's 9mm Heavy Q buffer in mine.

http://www.heavybuffers.com/ar15carbine.html

As for the DDLES lowers... They are SWEET! I need to get some new pictures of it uploaded, but here is mine in its original configuration as a pistol build:

...and a bit more recent, with the can...

Jon_L · Nov 13, 2011

I'm waiting for them to do their Glock-compatible lower before I invest in one, but they do look great.

9mm AR15 Build

giggitygiggity

Member

451 Detonics

Member

Jon_L

Member

Walkalong

Moderator

Attachments

Captain33036

Member

Taurus44

Member

Jon_L

Member

Similar threads