9mm ARs

[mycrstuff]

All these answers have given me some ideas. the bad thing is the parts or rifles that were in stock yesterday are out of stock today. If anyone else has any more suggestions let me know. You guys have given me more info than a few days of searching the internet.

[sigstroker]

I heard you lose velocity on 9mm after 10” on a barrel so it would be a range toy. There are adapters but be aware need to make featureless since most of those adapters aren’t compatable with Mag locks. If that route 9mm dedicated lower is an option.

Unlikely. I know my 16 inch turns subsonic ammo into supersonic because I can hear the crack.

As the 9mm is not mil spec... if you don't tinker, can you buy a complete gun?

If it does not feed or cycle right, you can send it in for work?

I looked for an upper that had some known compatabilities with the lower that I had. Foxtrot Mike tested their upper with 4 different lowers and the PSA was one of them. I know it won't work on a Colt mag lower because Colt mag lowers have a higher ejector. That was from a few years ago. I think most AR 9mm bolts are now cut with a higher slot to accommodate both ejectors.

After the lower and upper, all you have to worry about is the buffer and trigger. 9mm buffers are usually longer so the bolt cycle is shorter. They're also heavier to slow down the bolt velocity.

For a trigger, any AR trigger will work short term. 9mm AR's tend to break triggers because of the high bolt velocity, so sooner or later you want to get a 9mm specific trigger. Or one with an innovative disconnector location like a Hiperfire or KE Arms SLT.

[someoneeasy]

If you're looking to go with the Slyvan adapter, I ordered one from here last year. Adapter and BCG for $170

https://www.omegamanufacturinginc.com/Omega-Deals-AR-15-Sylvan-Arms-9mm-Magwell-Adapter-United-Defense-9mm-BCG_p_7066.html

I ended up picking up some dedicated Blem Aero lowers last year for $93ish so built those instead.

I'll be assembling a lower for my uncle with the adapter, no experience with it so far, but from messing around with it, it seems like it'll work fine.

[bigboyshooter]

[nitroxdiver]

[nitroxdiver]

For a trigger, any AR trigger will work short term. 9mm AR's tend to break triggers because of the high bolt velocity, so sooner or later you want to get a 9mm specific trigger.

Very good point! Colt 6951 uses stainless steel trigger and hammer pins that are stronger than milspec pins. Colt had issues in the early developmental stages with busting trigger and hammer pins especially on f/a subguns according to small arms solutions.

[j6p2004]

Any experience with CMMG 9mm RDB and their ARC magazine adapters?

[beanz2]

Any experience with CMMG 9mm RDB and their ARC magazine adapters?

[mnichols]

I went with a mag adapter in a standard lower, works great.

https://mcsgearup.com/9mm-colt-magazine-magwell-adapter-usa-made/

I also went the colt/uzi mag route instead of Glock... Can't say it's any better or worse, I just didn't like the way Glock mags slant backwards out of the mag well.

I used a complete PSA upper and a heavy buffer.

It runs great, but is heavy. Fun range toy.

[ysr_racer]

After I got my CMMG Banshee, my direct blowback CMMG Mk9 felt very snappy in comparison. So I converted it to their RDB system too. I also added a Kynshot hydraulic buffer and used a Tubbs flat wire spring.

Is the RDB conversion just a bolt carrier swap, or do you have to change the barrel too?

[beanz2]

Is the RDB conversion just a bolt carrier swap, or do you have to change the barrel too?

Barrel and bolt carrier group swap in the upper. For the lower, removal of ejector and replacement of bullet guide, magazine catch and bolt hold open lever.

[ysr_racer]

Thanks, what does SBN mean here?

https://cmmg.com/barrel-and-bcg-kit-16-4140cm-sbn-9mm

[beanz2]

Thanks, what does SBN mean here?

https://cmmg.com/barrel-and-bcg-kit-16-4140cm-sbn-9mm

Salt bath nitriding:

https://www.ibccoatings.com/salt-bath-nitriding-ferritic-nitrocarburizing-dhn-dhfnc/

[sigstroker]

I went with a mag adapter in a standard lower, works great.

https://mcsgearup.com/9mm-colt-magazine-magwell-adapter-usa-made/

I also went the colt/uzi mag route instead of Glock... Can't say it's any better or worse, I just didn't like the way Glock mags slant backwards out of the mag well.

I used a complete PSA upper and a heavy buffer.

It runs great, but is heavy. Fun range toy.

Nice thing about Colt mags is they have a reliable lrbho.

[morrcarr67]

All these answers have given me some ideas. the bad thing is the parts or rifles that were in stock yesterday are out of stock today. If anyone else has any more suggestions let me know. You guys have given me more info than a few days of searching the internet.

A lot of people tend to like the NFA stuff. Many people recommend them by name. Something a lot of people don't realize is that NFA is a huge OEM manufacturer.

They sell their patented lowers and uppers to several other companies. One of those companies is Dirty Bird Industry.

One of the biggest companies selling Dirty Bird stuff is AR15Discounts.com they are currently running a sale on the DB9 lowers https://ar15discounts.com/products/d...ower-receiver/

They are also running a special with the matching NFA stripped upper with the LRBHO feature https://ar15discounts.com/products/d...-receiver-set/

They also offer a complete upper (currently OOS) if you just want to put the two together https://ar15discounts.com/products/d...omplete-upper/

If you don't care about the LRBHO they have this upper in stock https://ar15discounts.com/products/n...pper-assembly/

Then you can put the lower together with whatever parts you want.

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