There are numerous owners on the ARFcom boards here.
I'm sure some will report.

Also, you can read the December 2004 issue of Small Arms Review, where there is a very good review of the system by respected gunwriter Jeff Zimba, who is also an ARFcom member.

Upcoming articles will soon be seen in NRA's American Rifleman magazine, and another writeup on the MGI upper along with the new Modular Lower receiver system in Small Arms Review.

My own experience with the system over 2 years now, has been one of nice accuracy, good zero repeatability, excellent reliability, and great versatility of use.

It is the very first quick change barrel system for the AR15 ever to use existing standard AR15 barrels, and was way ahead of the pack 2 years ago, and still is.

Designed by the man who designed the M2HB-QCB 50cal quick change barrel system for FN. He knows how to make a quick change barrel system, among other things.

The latest spec QCB from MGI includes internal dimensional changes which will accommodate AK47 mags, when used with our upcoming new MGI Modular Lower Receiver system that has interchangeable magwells. This will be a package that breaks new ground in modular options for the AR15 weapons platform.  Again, we have gone where nobody else has gone before, and got there first, with the best. If you want "cutting edge" items that are actually purchasable on the commercial market, and not just "future pie in the sky", MGI is the place to watch.

Hi Loaded Drum,

I'm about as "inside" MGI as it gets.
Over 5 years with the company, collaborate and assist on designs and testing, do marketing and sales, and customer support. You'd have to talk to Mack himself to get any more inside than me.

We currently do stock versions of the QCB with the longer bottom rail on it.
This rail extends back as far as the beginning of the release levers on the bottom.
It won't allow VFG mounting all the way back, but it will allow mounting about 3" forward of the hinge pin. I've talked with Mack about moving the levers, but it is not possible with the design.
It's $45 more, and generally we have them on hand at all times.
Since we make more of the other style, sometimes we run out of the longer bottom rail version, but we do try to keep them in stock as best we can.

Even if we run out of stock on the longer bottom rail versions, it's usually only a couple of weeks till they are re-stocked. Pretty sure we have some right now.

Yes, we now have the "friction fit", with 3 "L-shaped" slots in the extension tube which engage onto 3 small screws in the FF tube, with a "push and twist" method. It is more secure than the friction fit, but uses the same parts, with these mods on them.

We're way behind schedule for the carbon fiber FF tube with modular rails, and I don't think that we'll see that till next year now.

Ryan,
Cool Pic!!!!!!!!!!!!!

That's the first time that I've seen the ABS 9mm barrel with the can on it!
It looks really, really cool!
Love it!!!!!!!!!!!

556cliff,
The MGI QCB barrel locking system is factory-threaded on to the special timed threads on the front of the receiver. It is a short cylinder shape, with a round outer diameter. The FF tube is sized to be a tight fit onto the QCB locking block, and is held in place by the side screws and the presence of the locking cam  rods that protrude thru the top on bottom on each side.
The fit is tight and secure, and holds the FF tube quite solidly enough to use with a bipod.
The unit is user-strippable for maintenance or parts replacement.

We plan to offer upgrades for the FF tube. This will come next year sometime.

The current-spec MGI QCB comes standard now with the internal relief-cuts required to use AK magazines, when pairing it with the new MGI Modular Lower with interchangeable magwells.

Here are some photos of the new MGI Modular Lower system.


Right side view with generic upper and scope on it, showing AR15 magwell installed.



Left side 3/4 view from below, showing detail of the mounting block.
Note the strengthened area around the hammer pin and the removable magwell capturing the hammer pin(anti-walk)
CMT/Stag arms is producing our design, and later will show MGI logo only.



Photo of the almost finished AK magwell on the left, and the original design prototype on the right.
Note the AR-style mag release button being used.
It allows the AK mags to drop free, and not be rocked-out like an AK would.



We'll have units in stock by Friday, but not enough to cover all the pre-orders.
There will be 200 units in stock by around Christmas time.


To change magwells, all you have to do is take out the front hinge-pin, pop out the detent that holds the trigger guard on the front, slide the magwell off the dovetail block, and slide the new one on. Then put the hinge-pin back in and clip in the trigger guard. Done.
In conjunction with our MGI QCB, you can then quick-change the barrel to a 7.62x39 barrel, swap bolt/carrier, and you have a full conversion to 7.62x39, using real AK magazines, on your gun.  The QCB upper is already milled internally to allow clearance for using the AK mags.

Oh, yeah. I forgot to mention that 9mm magwells, 45ACP magwells, rimfire magwells, and others will be coming along as we go.

We're estimating $500 for the lower with the AR15 magwell, including lower parts kit.
The AK magwell is estimated to be $150 extra.
A modded bolt carrier will be needed for using the AK mags in the system, and we will have one available for purchase.

That's a good one, Marty!!!!

Out of spec barrel extensions can be relatively easily hand-fitted to the QCB system.
I've had to do it a few times, and I can provide instructions to users, if they happen to encounter something like that.

I knew about that lower a little while ago but saw a picture for the first time in some gun mag that I had bought to kill time in some doctor's waiting room. I actually said "Oh sh*t!" outloud.


Pretty cool

Marty,
Please do!!!!!!!!

I'm very interested in all of your projects.
You are doing some very cool stuff!

We're very pleased that our MGI QCB upper is making your testing much easier.

There's no telling what Marty(the "mad scientist") terWeeme will come up with, now that there is more flexibility in magwell size and shape!

Thanks!

Here's another nice photo showing the AR magwell detached, for detail of both halves. I liked this photo so much, I used it for my avatar.





Yes, yes. I'll be coming along shortly with the finished photos of the AK magwells too.
I'll also have photos of the modified bolt carrier, and photos of the QCB upper's internal relief cuts.
We're about ready to roll, guys!
These parts are the basic centerpiece of our SCAR platform.

As is shown in this photo, the rear half is serial numbered, and also marked "CAL-MULTI"(barely visible in the upper right corner, over the selector). Also, you can see that they are being manufactured for MGI by CMT/Stag, and later versions will only have MGI rollmarks, but will still be manufactured by CMT. This photo shows some nice close-up detail of the left side. You can buy as many different caliber magwells as you want, and use them all on the same serial numbered receiver(back half). In addition to AK47/AK74, and AR15, we'll also have magwells for 45ACP(Grease Gun mag), 9mm(mag TBD), rimfire calibers, and others as we go along. Belt feed module is also pending, as a slide-on module.




Presently, we are contemplating naming the system, "M.A.C.K.-16" for Modular AR Conversion Kit -16. Whaddya think?

Great idea about the 308 magwell/AR10 upper.
We're contemplating the possibilies of something like that .

About the name, Mack Gwinn sort of liked it.
We were also considering "Phased Plasma Rifle inthe 40 Watt Range".
Or, "Murderous Fire Breathing Bringer of Instant Death".
But, we couldn't fit it all onto the receiver.


How about, "Variable-Nozzle Bullet Hose"?

Adam,
It won't be until next year.
We have the design ready, but it is held up at the prototype stage right now.
He's informed us that he won't have the prototype ready until after the first of the year.

In the meantime, you can  drill a small hole and put a small sheet metal screw thru them to hold it in.

Admittedly, this has been an issue, and we are working on the resolution.

LaRifleMAN,

SWEEEEEEEEEEEEEET!!!!!!!!

I'm running a CQB as my test fire upper now too.
Thanks Marty.

I have always thought that the locking levers would be better on top so I can slide my hand back against the mag well.
I suppose they would be too close to the rail for some accessories, but then it's the same deal on the bottom if you want a VFG really close to the magwell.

Tom-

What's the optimum thickness for barrel extension flanges to be used with a CQB?
I have run into quite a few barrels that are loose enough to move around by hand when full latched into place on my upper.

Does not matter to me as I am only function firing, but I would like to know the right dimension so I can pick through my box of extensions when someone orders a barrel to fit a CQB upper.

Randall,
There is a rather crude but effective adjustment procedure that is built-into the MGI QCB lever system.

Give me or Mack a call, and we can walk you thru the procedure.

In the meantime, I'll try to get some info on a good average barrel extension flange thickness for you.

Quoted:
Unless those barrels are cheap and out of spec...quote]

I make all the barrels myself.
I use LMT, Rock River and DPMS barrel extensions.
My CQB is an early one from what Marty told me when he sold it to me.

I'm guessing that my CQB is just a little on the loose side.
It would seem pretty simple to tweak the locking arms to make the locks close down further.

I have had a few barrels that lock in really good and tight.
There is definetely some thickness variation within the makers of barrel extensions.
My guess is that all of the extensions are within the spec and that the specs are loose on purpose.
In a traditional barrel nut and receiver situation, the thickness variation from barrel to barrel would never matter.

It does not bother me one bit that they are loose because I am only using the upper for function firing.
I usually don't even have any sights on the uppers.