AR 9mm

[CZU]

I've had an itch for a 9mm AR for a couple months now. Started asking around and found that it's not just a matter of picking up mil-spec parts or just going out there and buying one off the shelf. I started doing the research and found that there are so many options for building these that it can be quite frustrating. For me, the first step was deciding what type of mags to use and from there would be picking the manufacturer of the lower and upper for these mags and choosing whether or not I wanted last round bolt hold open. After those decisions are made it's then a matter of choosing the BCG, type of buffer, stock or brace, etc. I decided on the MP5 style for this one even though there would be no LRBHO, New Frontier Armory C5 upper and C5 lower, Maxim defense 9mm bolt, JP Enterprises SCS 9mm buffer, 10" stainless barrel, Maxim defense CQB stock(I had to borrow the brace portion from another pistol for obvious reasons), everything else is standard AR15 except for the trigger. I had a Rock River Arms 2 stage that I used. The scope is a Nikon P223 that I boresighted, can't wait to get it on some bags for further adjustment. After a 100 rounds, I haven't had any malfunctions and I'm getting 2-3 inch groups @25 yds while standing. I've tried 3 different mags from different manufacturers without problems. So far I'm satisfied with the result.(Some of the parts were used, the buffer, the CQB stock, the Maxim bolt. These items were about 50% of what you would normally have to pay).

 

[loc n load]

Nice job. I am sure it will be a shooter. You obviously put some thought and research into it. Interesting lower that uses the MP 5 mags. I have an AR9 Rock rivers that I have shot for probably 10 years. Use metalform mags in mine, the same one's I used in the Colt SMG for years. Enjoy your new AR.
Mine does double duty as a trainer for folk's that I am acclimating to the AR system and as one of my " go to " house guns.

 

[BB57]

I bought a 10.5" AR-9 pistol from RRA parts (which actually has an 11.25" barrel) and added a brace and a Burris Fast Fire III.

I ended up adding a free float rail as well and the end result is 2 MOA accuracy at 100 yards with 115 gr XTPs or HAPs at about 1550 fps.

I also built a 16" AR-9 carbine using a PSA upper half. However accuracy was poor. I replaced the barrel with a 16" ballistic advantage barrel and then replaced the upper with an RRA upper.

In both cases I'm using a KAK 10oz buffer with sliding weights to manage the recoil of the fairly hot loaded 115 gr bullets, manage bolt bounce, and prevent breaking the bolt stop.

The carbine has a Burris AR-332. You can see the PSA upper half near the top of the picture.

Both of them are using Colt pattern magazines which provide for LRBHO.

I had a large number of Uzi magazines and they work fine as well with some modification, although they don't have the follower needed to activate the BHO. Uzi magazines are stamped, folded and tac welded, and they are hard. I had to spot anneal them to mill the cut for the magazine catch.