Anybody got any experience or info on this particular adapter?  Similar concept to the Stern Defense setup.  I'm looking for something that will let me use CZ 75 mags in a 9MM AR.  

Some info from their website -
*Only compatible with mil-spec AR-15 lower receivers, combined with a 9mm upper with a Glock-cut bolt.
*No last round bolt hold open.
*Hand-fitting may be required with FM-9 uppers.
*The MagX will not work with the CMMG Radial Delayed Blowback.

According to an internet search, the upper needs to use a Glock cut bolt and does not provide a hold-open feature after the last round is fired.

I was considering one for my pistol caliber build, but was a little turned off by the blow-back operation of the 9mm upper.

Went with a DI upper from Macon in 45ACP instead.

Guess to answer my own question, just got one and it works pretty well.  

When I first checked their website, I didn't realize the CZ magwell wasn't available until the end of the year.  Checked it a last week and they were in stock ahead of when I expected!  Ordered one and got it in my hot little hands within a couple of days.

The important parts:
- Anderson lower
- Aeroprecision EPC LRBHO upper
- Macon Armory Guaranteed To Feed 5" barrel
- FM9 bolt
- Expo Arms 9mm Extended Carbine 8 oz solid buffer
- And of course, a CZ 75 Matador Arms Mag-X adaptor

Initially, the parts were pretty much plug and play although I had to mortar the pistol slightly to pull the charging handle and bolt back.  Turns out the bolt lower lug was binding on the X-MAG feed ramp.   Took some metal off the top of the ramp to fix that problem.  Dummy rounds fed and ejected with no problems.

Matador Arms tells you the their magwell does not have LRBHO.  I have had good luck with the NFA LRBHO upper in the past and noticed that Aeroprecision now makes one so I thought I'd give it a try.  The bolt locked back with no problems.

In my hurry to order parts, I didn't notice that the Expo Arms buffer was solid steel.  I wanted a dead blow bolt.  Chucked it into my trusty Craftsman drill press and used a 1/2 inch drill bit to remove 2 ounces of steel.  I then added some tungsten powder I had sitting in my parts box to bring the weight back up to 8 ounces.  The tungsten filled about 2/3 of the 1/2 inch hole so now I have a home made dead blow buffer.

During the first trip to the range to sight the gun in and function check things, everything worked great with 115gr and 124gr FMJ.  Hollow points?  Not so good, was getting quite a few nose up jams with the front of the rounds catching on the top edge of the feed cone. That's going to take a little work.

So overall, I'm pleased with the CZ Mag-X adapter.  If you're looking for a range toy to bang away at paper and steel, and you have a couple CZs, this just might work for you.

Later,
Pete



Tried out the upper on my SBR and AR 15 pistol just for grins.  Works!

It was my understanding that the Aero EPC upper has the LRBHO mechanism and is designed to work with the EPC lower, which doesn't use the common ping-pong paddle bolt lever.  So I'm surprised it worked with the Anderson lower.  Did you have to remove the pin-pong paddles?

I was using the Stern magwell adapter, and that had a LRBHO that worked flawlessly.  Since then I've primarily switched to a CMMG radial-delayed blowback system and use the CMMG-specific versions of the Endomag inserts for PMags.

Didn't have to change anything on the lower.  The bolt release (ping-pong paddle?) worked just fine.  I've had Stern's magwells before, but I wanted an adapter that would let me use CZ 75 mags.  Stern didn't have one last time I checked.

One thing I will mention.  I tried the upper and Mag-X adapter in 3 different Anderson lowers.  It worked fine in all three, but there was a noticeable difference in how tightly the adapter fit in the lower magwell.  The fit is very tight in the 5" AR9 - I can lock it in by hand, but have to use tap it out with a rubber mallet.  The lower with the brace was also a snug fit, but I could install and remove the adapter easily by hand.  The SBR was the loosest fit with no resistance.  The adapter could drop free if I hit the AR mag release.  Guess just some examples of tolerance stacking one way or another even in a supposedly mil spec lower marketed by the same manufacturer.

it actually will work with the CMMG, i use one, you just need remove the extractor

Other than removing the extractor, was it plug and play?

I did polish the feed ramp a little bit, but that's just me.

I have a CMMG RDB 8" upper and tried it out with the Mag-X.  I had a to take some metal off the top of the adapter feed ramp plus I seated it a about .025-.030" deeper in the lower.  Works like a champ!

I've been chasing a FTF feed problem with a couple of different blowback barrels, especially when the mags are topped off, but now I just have top find a 16" RBD barrel and bolt for my build.  In the mean time, I'll just stick the adapter in my 556 SBR and use it with 8" upper every now and then.  Thanks for the tip.

Pete

Did I say "champ"?  I mean't "chump".  Hand cycling worked last night at the work bench.  Running at the range today - not so good.  Oh well, time to quit messing around with Dremel tools and jeweler's files and get medeivial on this thing.