This is the New Frontier Armory S-9 lower that takes CZ Scorpion mags. It is so new that it isn't yet listed on their webstore and my serial number is in the low single digits (!). I'm one of the first to get my hands on one of these. I'm planning to pair it with a CMMG RDB and Gibbz side charging upper once I get some parts. I'll start with pics and give some info and thoughts on the lower.





Standard for NFA: threaded bolt catch pin, set screw for rear takedown pin detent hole, receiver tensioning screw.


Feed ramp appears to be identical to the one from the C-5 (MP5) lower.


Ejector is secured by two set screws and a machine screw. It also has a tab to contain the LRBHO actuator.



The LRBHO actuator.


Ejector, screw and LRBHO actuator removed.



Magazine release in relation to the trigger pin holes.


Reach to the magazine release. (I have large hands JSYK)


The tab on the ejector interferes with a standard upper receiver.



Standard upper would require some modification for clearance of magazines.


Weight is 14.2 oz


FURTHER INFO AND THOUGHTS:
Magazine well is tapered.
If you don't want to modify an upper, you will need to use the NFA C-5 or Gibbz G9 upper. However I think it will take less material removal for proper clearance vs the MP5 magazines.
I'm ambivalent about the LRBHO they have come up with. It seems a bit chintzy and I don't like the way it's held in place, but it does allow you to use the standard BHO so I'm okay with it (pending operational tests).
Will not work with Magpul BAD lever or certain aftermarket BHOs without modification due to clearance issues. Honestly this is the biggest gripe I have with the lower.
Magazine release will interfere with anti-walk trigger pins that have a connector between the pins.
The magazine release is REALLY extended. It's not particularly ergonomic for my hand size/preferred pistol grip, YMMV. An AK style release would've been cool, but it's not a deal breaker by any means.
It should be fairly easy to modify to work with the CMMG RDB system. Modifying the feed ramp to clear the bolt will be the biggest thing. Replacing the ejector with a simple piece of bent sheet metal to hold the LRBHO in should be no problem.

Overall I think this will be a fantastic option as the Scorpion mags are the (IMO) best current 9mm PCC mags. I have 4 of the Magpul EV-9 mags coming shortly, so watch out for further pics. Next order of business is to start modifying to work with the RDB system, will post updates. Let me know if you have questions or want any other info on the lower.




UPDATE 7/30
Magpul EV9 mags arrived. There are issues with the RDB setup.


There is no overtravel stop. The intention may be for the relief cuts in the C-5 upper to keep the mags from moving.


Mag pushed as far up as it will go.


In order for the RDB bolt to ride low enough to strip off rounds, the 4 and 8 o'clock lugs have to be practically sitting on the feed lips.


The feed lips will clear the bolt, but the rails on the bolt carrier will run into them.



The feed lips on polymer mags are too wide and flat to allow use with the RDB bolt. I contacted Macon to see if the bolt carrier could be modified for clearance, but it didn't sound like that would work due to too much of the rails needing to be removed, potentially causing carrier instability issues. I ordered some of the Manticore Arms mags with steel feed lips, they are much thinner than the Magpuls and may work without modifying the carrier.

FURTHER INFO AND THOUGHTS:
The LRBHO spring needs to be cut down/weakened to work properly, since the pivot points are very close together it loses much of the mechanical advantage.
I'm interested to see if the Mean Arms roller delayed bolt will have enough clearance to use with these mags. That may be the way to go.

UPDATE 8/6
I got some of the Manticore Arms Scorpion mags with metal feed lips, they have plenty of clearance with no modifications needed for the RDB carrier or the mag release. So if you are okay with using just these mags, you can get it running with minor modifications (removing ejector, trimming feed ramp).

Pros:
*Less modification needed
*Activates the LRBHO better than the Pmags.
*Fits more snugly, less play in all directions.
*Steel feed lips and transparent mag body.

Cons:
*Harder to find than any other Scorpion mags.
*Doesn't drop freely.
*3 fewer rounds compared to Pmags.
*Magwell scrapes up the 12 round marker and you can't see it when inserted



This is the feed lip mod, only necessary to clear the RDB bolt and carrier. I just used a belt sander to shave off about 1/8 and then radiused the edges.

UPDATE 8/25
IT LIVES!






So the Gibbz G47 upper does work. The mag overtravel stops need to be shaved down to clear the feedramp, and a slight relief cut for the LRBHO retainer is necessary. So far it only works with Manticore Arms hybrid mags, will have to see if it can be modified for Magpuls, etc., but it is running so I'm happy for now.

BUILD LIST:
NFA S-9 lower
Gibbz G47 upper
CMMG Guard 8" barrel+bcg
SBA3 brace
Midwest Industries Combat Rail
Magpul K2 grip
Strike Industries Multi-Function Endplate, flat-wire spring with H buffer, and Cobra AFG
Rise Armament RA-140 trigger
Seekins 60 degree safety and Rook flash hider
PRI fixed sights
Manticore Arms Hybrid Scorpion mags

That’s a nice piece for sure! When it comes to the modification to the upper for the proper fitment is there video online or pics? I’m afraid of butchering a new upper...

Once my mags come in I have a junk upper receiver I'm gonna do a practice mod on, I'll post pics.

What bolt are you using with the scorpion mags?  Does the CMMG stuff already work with these mags?

Interesting.  

Good luck.

I'm gonna be using the radial delayed bcg. As far as compatibility, well, I have no idea! Scorpion mag lowers aren't yet common enough for info on that. But tinkering and figuring out new ways to do stuff is half the fun anyway.

They ruined it for me with the full size magwell.  And I was so looking forward to this.

I understand your feelings, I am also mildly disappointed by that. Something like the Wraithworks Warscorp-9 would've been ideal, but that gun is currently vaporware and might have proprietary receivers anyway. Maybe if NFA releases a raw lower you could mill off a bunch of the magwell before coating it?

Which they could easily do before they anodize.  I will just stick with my Endomags.

Looking forward to seeing your results, I think you should have success and worst case may have to relieve the mag release a bit to lower the feed height.

BTW, not trying to be a jerk but you keep calling the ejector the extractor in your original post.

You're right, I always mix up the two. At least I'm consistent! Fixing now.

Please post a pic with a mag inserted once your mags arrive.

This interests me.

Concur.

Bump for update.

Thanks for the updates and pictures.

The full size lower doesn't look out of place with the scorpion mag....in my opinion. It looks much better then a full size magwell/lower with a glock mag. I am not anti-glock mag, just hate the look of them in a lower that isn't sized for them.

I have been eyeing the MP 5 mag version from NFA, but have no MP 5 mags........honestly, I have no scorpion mags either, but scorpion mags (as we all know) are much cheaper and very plentiful with a number of manufacturers.

Even though I would have to buy scorpion mags, this could be a fun 4th 9mm AR build......haha. If nothing else, just for the looks of the nice curved mag:)

Good news! The Manticore Arms Scorpion mags with metal feed lips have plenty of clearance with no modifications needed for the RDB carrier or the mag release. So if you are okay with using just these mags, you can get it running with minor modifications (removing ejector, trimming feed ramp).

Pros:
*Less modification needed
*Activates the LRBHO better than the Pmags.
*Fits more snugly, less play in all directions.
*Steel feed lips and transparent mag body.

Cons:
*Harder to find than any other Scorpion mags.
*Doesn't drop freely.
*3 fewer rounds compared to Pmags.
*Magwell scrapes up the 12 round marker and you can't see it when inserted

Ya it's not as bad as I thought.  If they milled off that lip on the lower leading edge of the lower it would look even better tho.

Agreed!

Any updates on this?

I'm currently waiting on the upper for this build, it is backordered. May be a hot minute til it's operational.

I got pretty excited when I found this thread.

I really hope it works out!

You mention trimming the feed ramp. Can you give more detail on that?

I keep getting excited about this, but then keep remembering that they don't even list the lower on their website yet....could be a long wait.

Still very interested though...very.

I took about 1/8" off the top of the feed ramp lips and slightly reprofiled them. I'll post a pic later. If you want to buy the lower, send them an email via their website and specify that you want to buy an S-9 lower. They will hook you up.

So if you wanted to just go simple blowback (maybe go RDB later) besides the upper needing to be wider in the mag area, will it run with a glock cut 9mm bolt?

Yes, it was designed for regular blowback bolts so it shouldn't require any additional mods for that. You could order an NFA C-5 upper as well and then you should be able to plug and play.


This is the feed lip mod, only necessary to clear the RDB bolt and carrier. I just used a belt sander to shave off about 1/8 and then radiused the edges.

That looks easy enough.

Since there doesn't seem to be any C-5 uppers available, did you ever try mill a normal upper to fit the wider mag? I know you talked a bit about it early on.

Do you know if the depth of the cuts to widen it are specific, or just do enough so the mag fits?

I have bolts/barrels to do either simple blow back or RDB.

I have emailed and received an initial response. Waiting to hear back about price. Thanks for the heads up.

I did make an attempt to modify a junk upper I had, however I don't have a proper milling machine so it didn't work very well. (I need a milling machine, someone please give me $$$)
I don't know the exact height of the relief cuts, but it would probably be about halfway between the mag at normal height and the mag pushed up as far as possible (as seen in the pics with the Magpul mags inserted).
I would probably recommend using simple blowback at this point, because it should work with no mods. Not everybody wants to tinker to make their gun function. Unless you are fine with just using the Manticore Scorpion hybrid mags, because the mods needed are pretty simple.

Little did I know, I already seem to have a C-5 upper!

Attached File


This is on my one blow back glock mag NFA lower with PDW brace.

If nothing else, I will be to try straight blowback and have the upper to be able to match the cuts.

I have a smaller milling machine, so should be pretty easy.

Knowing that I have this....makes me feel more positive about ordering the lower...once they get back to me with price....hopefully Monday.

Attached File

Well, I bought a scorpion magpul mag locally today.

I guess I have to buy the lower now;)

Another option for an upper is to use one modified for AK mags like the PSA Gen 1 KS47 upper.  (I say Gen 1 because the Gen 2's have stops in the upper to prevent over insertion of an AK mag which I don't if they would interfere with Scorpion mags...although I presume you could cut them off if they did).

I have several old DPMS Lo Pro's and Hi Riders that were clearanced for AK mags and drums which I think would work fine also.

However, I personally would go with the PSA upper since the CMMG RDB retains the use of the forward assist and the KS47 upper still has that so it would be usable (I know some people hate the FA but that is another discussion).

Funny you should say that, I am waiting on a Gibbz G47 side charging upper to complete this build. I would use a normal C-5 upper but you need the cam pin slot and full length ejection port for the RDB to work properly.

I was just looking at those uppers too. Hopefully you have it soon.

You cost me $213.99 today.

Let the games begin!

Picked mine up from my FFL today.

Looks real nice.

It will not work with my bufferless upper set up that I pictured recently.

That is ok. I want to build a whole new pistol anyway.

This will just be straight blowback. I have a CMMG RDB setup, so this will be fine as normal.

How long are the Gibbz uppers taking to get?

Attached File

I ordered the upper on 7/23 and it's on the way, I should have it Monday. Still listed as backordered, they are probably trying to fill all their orders. So probably a month or less. I'll post more pics when it comes in. Definitely excited to get this project running.
(Oh, and just curious, is your serial number still in the single digits?)

I forgot about that. Yes, single digit.

I have found a couple C-5 standard uppers im stock. Can't decide if I want to go side charger or not. If I go side charger, I will go with the Gibbz with the latching charging handle.

I was looking at my bufferless upper again. I know it is a C5 cut receiver, so why wouldn't my mag fit inside the upper????

I am beginning to think that the Magpul mags are a different geometry at the top (like you showed in regards to working/not working with the RDB bolt) to fit inside the upper deep enough.

I will have my NFA "certified" C5 stripped upper on Thursday and I will be able to double check. I wouldn't be surprised if unmodified magpul mags do not slide in and latch with the upper in place. It looks like a very easy fix, by removing a small about from the top outside edges of the mags.

I also have a couple PSA AK 9mm mags coming to try as well.

Also....ended up with 2 S-5 lowers, so one may be a simple blow back and one may be RDB.....after you figure all the RDB mods out for me:)

I hope you don't mind me posting in your thread. Just hope people find it interesting.

IT LIVES!






So the Gibbz G47 upper does work. The mag overtravel stops need to be shaved down to clear the feedramp, and a slight relief cut for the LRBHO retainer is necessary. So far it only works with Manticore Arms hybrid mags, will have to see if it can be modified for Magpuls, etc., but it is running so I'm happy for now.

BUILD LIST:
NFA S-9 lower
Gibbz G47 upper
CMMG Guard 8" barrel+bcg
SBA3 brace
Midwest Industries Combat Rail
Magpul K2 grip
Strike Industries Multi-Function Endplate, flat-wire spring with H buffer, and Cobra AFG
Rise Armament RA-140 trigger
Seekins 60 degree safety and Rook flash hider
PRI fixed sights
Manticore Arms Hybrid Scorpion mags

Thanks for the pictures, it looks great. I don't think the mag well is full sized, I just think the geometry and material of the skorpion mags necessitates a bigger magwell.

Nice work!

Great build!

I just order what NFA says is their last S-9 lower in stock.  This should be a fun one to put together

$$$?????

I know you aren't asking me, but mine was $213.99 to my FFL.

Thank you

I probably helped them sell a couple of those

2 to me....I got consecutive SNs.

It's pretty cool to have low consecutive SNs, even if they are only AR lowers.

I agree.

I do thank you for this post, I wouldn't have known that they existed.

It was sheer luck on my part that I happened upon a picture of a NFA lower with a scorpion mag, probably SN 1 or 2. Otherwise I probably wouldn't have bothered contacting them to see if they were available.

Same here.

Definitely!