Edumuhcate me on AR9's / 9mm AR pistols

#21
I've assembled several for myself and a few for friends/family. Anecdotal, however:

Lowers used:

New Frontier C9
PSA non-LRBHO
PSA LRBHO
QC10 LRBHO

Uppers used:

RTB Nickle-Teflon coated uppers
Anderson standard uppers
Anderson lightweight uppers
I've never used a dedicated 9mm upper

Barrels:

Ballistic Advantage in 5.5" , 8", 11", and 16"
KAK 8"
Spinta 7/5"

Bolt Carriers:

New Frontier and Spinta BCGs

I've lego'd the above in various configs over several years and the only combo that has given me issues with the KAK barrel on a RTB upper with the PSA LRBHO lower. All of the others run like clocks. Love 'em. PSA LRBHO lower has the same issues as the QC10 in that it does not reliably hold the bolt open. My favorite is 5.5" barreled upper running a 9mm can with subs. :)

I've also tried out a few adapters just to see how they work out:

Sylvan Arms:

I've run this on BCM lower, PSA lower, a few Anderson lowers, and a 80arms (self-finished) lower with excellent results (YMMV). Easy to install. Take a bit of getting used to the magazine release location (you keep wanting to use the normal mag release). Factory glock mags do not drop free, ETS mags do drop free (most of the time).

TorkMag two-piece adapter:

I picked this up specifically because I just wanted to see if/how it would work. Silly thing, but it does all you to use the standard magazine release if you ware willing to make a cut in your factory mags. I was very surprised at how dead-on reliable it has been. It is still sitting in a random Anderson lower.

Stern Defense MAG-AD9:

Luxo adapter that, unfortunately, has been the least reliable of the three I've tried. Pros: mag-release is handy, if still less intuitive than normal AR mag release. LRBHO that actually works. Easy install. Cons: I've only been able to get it to run reliably with one lower/upper combination.
 
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#24
Another 100 through it today with no issues except when chambering a round after a mag change and I get lazy running the charging handle. Only the second time I have shot it with factory ammo. First time was with my reloads which it didn't care for. For anyone on the fence, I think an AR9 is must have for cheaper AR fun. No way I'm going to stand 15 yards from a steel plate with a 5.56 AR and pound a way. Quick to kill your steel!
 

tdyoung58

NNLP 31st Batt
Forum Supporter
#25
I have a ATI AR9 ... Uses Glock mags, which is nice because I have a Glock 19 to go with it. It's perfect for HD with the light
Only drawback is it's only a 5" barrel and doesn't have a bolt hold open for the last round. Other than that it's been great.
Added the STG brace, Red Dot, 500l light and forward hand guard
 

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#27
I ordered a 5.5BA barrel, a KAC 3.25 muzzle device, and a BCG. I need a rail, any recommendations? NFA is out of the 7” MLOK or I would get that. 7” should fit if you add 5.5 +3.25 the subtract out the 1” that’s part of the receiver extension and the .5” as part of the thread overlap.
 
#28
Budget?

I am partial to Midwest Industries. They have a nice 7" M-Lok MI-G3M7-BLK (if you can find it on sale, Primary and DSG have sales on MWI quite often). Should be around 100 when you can find it discounted/on sale.

Those NFA rails look like friction fit, very similar to the basic Matrix rails. Neither seem to have any type of receiver tabs/indexing, so if you like the NFA rail, you can find the similar Matrix rail for around 50 at JoeBobs (Matrix Arms AR-15 Foxtrot M-LOK Handguard). I am not a bit fan of rails that don't have some time of indexing/retention/receiver tabs, however.
 
#29
Good to know. Like the title of the thread suggested I’m a total noob on the platform. I like MI I’ve had one of their 15” on an AR for years.

Budget?

I am partial to Midwest Industries. They have a nice 7" M-Lok MI-G3M7-BLK (if you can find it on sale, Primary and DSG have sales on MWI quite often). Should be around 100 when you can find it discounted/on sale.

Those NFA rails look like friction fit, very similar to the basic Matrix rails. Neither seem to have any type of receiver tabs/indexing, so if you like the NFA rail, you can find the similar Matrix rail for around 50 at JoeBobs (Matrix Arms AR-15 Foxtrot M-LOK Handguard). I am not a bit fan of rails that don't have some time of indexing/retention/receiver tabs, however.
 
#30
Need to check the ID of whatever rail you are looking at to make sure it will fit that flash can's OD. The MI rails are pretty slim. Better to know it will fit before spending money :) KAK makes two different diameter version of their flash cans, normal and slim-line.
 
#31
Yes. I got the slim device for that very reason.

Need to check the ID of whatever rail you are looking at to make sure it will fit that flash can's OD. The MI rails are pretty slim. Better to know it will fit before spending money :) KAK makes two different diameter version of their flash cans, normal and slim-line.
 
#35
The BA 5.5 barrel I ordered never came in, so I ordered from a different place. I also noticed the 7” Mlok rail was back in stock so I paid for one of those. I think $16.00 shipping is to get people in the store. As much as I hate driving to N Vegas I’m not paying $16 in shipping. Hopefully next weekend I’ll be able to go out and shoot it.