Hi guys, thanks for tuning in to another video on ForgottenWeapons.com.
I'm Ian McCollum, and today we are taking a look at a CMMG Banshee carbine.
This is a 9x19mm adaptation of the AR-15.
And you may be wondering how on earth is that
relevant to Forgotten Weapons? Like these things
just came out a couple years ago, what are they doing here?
And the answer is this has a fantastically clever and interesting and novel operating mechanism to it.
So, to go into the backstory a little bit. CMMG kind of first came to notoriety
for their conversion of the AR to use 7.62x39. And in the wake of that being kind of a big hit,
certainly generated a lot of interest,
they decided that they wanted to expand and do other calibre conversions.
And the first one they decided to look at in 2015 was a pistol calibre conversion, specifically .45 calibre.
The idea for pistol calibre ARs was out there, and like everybody and their brother was working on a 9mm PCC AR.
And so CMMG decided that they'd buck the trend a little bit, they'd do something novel and go with .45.
So they spent quite some time developing a simple blowback .45 calibre AR conversion.
And the problem is they could never quite get it working 100%.
They did a lot of development on it and what they found is they just had this 1% or 2%
failure rate where the ammunition wouldn't quite feed.
They were using Glock magazines in a lower that was specifically made to use Glock magazines
Ultimately, they put this thing under some high-speed cameras. And what they discovered was that
when the bolt carrier hit the back of the receiver at the end of travel
(that's when the whole gun tries to impart its recoil impulse to the shooter),
and that backwards chunk of the gun when the bolt stops and then tries to push the gun backward,
that has the sympathetic effect of pushing the ... top round in the magazine forwards.
And what they found is that top round would bump forward like every time when the bolt hit full travel.
And about 1% or 2% of the time it would come ... far enough forward
that it would actually half pop out of the feed lips, and it would cause a feed issue.
And they realised at that point that they didn't really have any good solution to this,
like simple blowback just wasn't going to work in this platform as they had that set up.
So they went to the other end of the spectrum, and they decided to instead use the
direct gas impingement (or quasi-DI) system in the AR-15 to run their their gun.
And they had the opposite problem there, they couldn't quite get enough energy out of the system.
So ... by the end of this development they were using a really big gas port right in front of the chamber.
They were blowing a ton of gas back into the action. They were getting just barely enough energy to cycle the gun.
So it shot really well because it was right on the verge of short stroking every time.
But the problem was it wasn't particularly reliable.
After every couple hundred rounds it would be dirty enough that it would stop working,
and that's not a ... recipe for commercial success either.
So they were actually like right on the verge of giving up on the whole idea
when they took inspiration from the Reising submachine gun.
This was a delayed blowback .45 calibre submachine gun that was adopted by the US military during World War Two.
And it's not the specific action that the Reising uses, which is sort of a tilting block, kind of.
It's not the specific action that inspired them, it was the idea of,
"Ah, there's another way. We don't have to use fully locked or completely unlocked, we can use a delayed blowback system."
So like this project was on its tail end and going out the door.
Management was kind of done with dumping money into this thing that was going to go nowhere.
So they whipped up three different ideas for delayed blowback systems.
And the third of them turned into what we have here today, which is what they call radial delayed blowback.
So let me pull this gun apart and show you how that works, because I think it's really clever and cool.
I'm also going to show you the magazine, because the magazine
is a seriously underappreciated and very cool aspect of the whole system.
So a couple things I want to touch on first. CMMG makes this in two different versions.
They do a version that uses an AR-15 receiver with converted AR-15 magazines.
And that magazine conversion is super cool, and we're going to look at that after we look at the operating system of the gun.
They also make a version of basically the exact same thing on a receiver that's set up to feed from Glock pistol magazines.
So that's why you'll see two different patterns of them out there.
Anyway, get into the guts of this guy. This is a totally standard,
stock AR-15 lower made by CMMG, but interchangeable with any other uppers.
So we're just gonna pop it open like an AR, and here's the special sauce.
What they did was make a couple of actually surprisingly small modifications to
the AR-15 bolt carrier and bolt. So the most significant one
right here you can see that the back of the locking lugs are cut at a 45 degree angle.
Here's a standard AR-15 bolt with, of course, square locking lugs.
And the idea of this is that these lugs rotate into battery
(like so, when this is all the way back),
and then they are firmly locked in place with a matching set of lugs in the trunnion.
And this can't open until the bolt carrier goes backward,
which rotates the bolt, which lines these up so that they can come out of the back of the trunnion.
The idea here is that you don't need to move the bolt carrier. Instead pressure on the bolt face
will cause these angled surfaces to push back and unlock the bolt on their own.
When that happens, as long as the ... bolt head is still in the trunnion, the bolt head's not moving forward.
It's actually the bolt [carrier] that is moving backwards.
Now, normally what we have here is a cam pin,
we still have a cam pin, and in a normal AR-15 bolt what happens is,
from a locked position, gas comes in here, it pushes the bolt carrier backwards,
and then the cam pin is used to force the bolt head to rotate as the carrier goes back.
What CMMG does is the exact opposite, it uses this same system in reverse.
Namely the bolt is ... being forced to rotate by these angled surfaces that are being pushed on.
That acts through the cam pin and forces the whole bolt carrier to move backwards.
... The cam pin acts as an accelerator lever, because the bolt head
can't actually come backward until this has made this amount of travel.
Now one of the other things that they did here was adjust the length of the cam track.
You can see that the standard one is much longer than this.
And that is one of those tweaks that you need to get the system to balance correctly.
But the idea is, just as in a levered delayed system or a roller delayed system,
you're using the lever or the rollers to force a heavy part to move before the bolt can move.
So it is in effect accelerating this backwards before the bolt head can move.
And they've used the radial motion of the bolt head to do that in this system, hence radial delayed blowback.
So we have the same basic forged parts here,
I suspect this is a totally standard AR-15 bolt carrier, which makes it more economical to produce.
Now, what's the benefit of this you might ask.
Well one benefit is the AR-15 was not designed to have a really heavy bolt carrier.
... Guns that were designed from the ground up as simple blowback pistol calibre carbines
have more mass in their bolt carriers and bolt groups,
so that they don't have the problem that CMMG ran into in the first place.
And frankly the problem that simple blowback AR conversions have to this day,
which is they tend to be pretty recoil heavy, snappy guns.
They open really on the fast side of safe. They are in fact safe,
but they open faster than you'd really like because there's not enough room to really have enough mass.
Now by switching to a delayed system,
they're able to take about half a pound of weight out of the operating components.
So this is a totally standard bolt carrier, this weighs about 11.5 ounces all put together.
(I'll get to this in a moment.) And then it's operating with a 3 ounce buffer weight.
Compare that to typically something like a 15 to 16 ounce 9mm blowback AR bolt,
in conjunction with a 5 or 6 ounce buffer.
There's about half a pound less weight involved in this, and it opens slower on top of that.
Now, that said, I do have a weight in the back of this. So CMMG added a hole here with a roll pin,
and they have a selection of weights. They have a 1 ounce, a 2 ounce and a 3.5 ounce weight
that you can add to the back end of the bolt carrier here.
I've added a 1 ounce weight. The balance that this allows you to tinker with
is more weight means the gun will open a little bit more slowly.
So for example, if you're shooting heavy bullets with a suppressor,
you're going to have a lot more force pushing back on the bolt head and it will behove you to add
more weight to the bolt carrier so that it doesn't open as quickly.
Now the other element that I wanted to show you here is the magazine. This is a standard, regular magazine body.
They have ... marked it "CMMG 9mm", but you can see up at the top here this is actually a PMAG in 5.56.
But it's got a very funky set of feed lips and follower.
So, what they have done is actually create a magazine insert, ... in fact, I shouldn't say they created it,
this came from MEAN Arms, who developed this magazine as
a system for people to use standard AR-15 lowers with pistol calibre uppers.
And there are a couple of reasons to do so.
One is that this will actually engage the bolt hold open in a standard AR-15.
For a 9mm gun using, say, Glock mags, you really need a substantially different hold open
because a Glock mag actuates the hold open from the front, not from the back.
Maybe more substantially, this means that if you've got a ... registered short barrelled rifle or a registered full-auto lower assembly,
if you use a magazine like this you can put a 9mm upper on it
without having to make any changes to the lower, which is really super handy.
So in addition to that there are some advantages that this has over a Glock magazine in general.
It is a constant curvature.
It's a double-feed, double-stack magazine.
So it's far easier to load than a Glock pistol mag, especially the last few rounds.
Because those pistol mags are typically, and in the Glock case specifically, they are double-stack, single-feed [mags].
So this tends to be a more reliable magazine system,
because the rounds stay in their same orientation all the way up until they feed.
Where in a single-[feed] magazine you're going from two stacks,
and then changing the angle to compress that magazine to a single feed at the top.
And this is just a self-contained unit that you can drop into any AR-15 magazine body.
So that goes in. The spring is self-contained inside that assembly,
so I don't have to worry about it springing out the bottom of the gun.
Just snap the floor plate on, and you're ready to go.
So CMMG had this radial delayed blowback system pretty well in mind by the beginning of 2016,
but they would spend more than a full year actually tweaking it before they were able to release it onto the market.
There really is a lot more fine tuning that goes into something like this to take it from
one or two handmade prototypes to something that's actually suitable for mass production.
And beyond that when you're looking at something in a commercial context like this,
it needs to run with a wide variety of ammunition.
So, 9mm is particularly bad in that respect, but even .45 ACP brings up a number of challenges.
Can you run high-velocity 185 grain bullets? Can you run some of the weird 200s that are out there?
Do you want to try and get it to run with semi-wadcutters?
And then of course there's the standard 230 grain ball,
there are going to be some higher velocity rounds, some lower velocity rounds.
And a gun like this is going to be used with all of those different types of ammunition.
And unless you want a lot of angry customers, you have to have a gun that'll run on basically any of it.
So throughout the whole of 2016 the company was tweaking and fine tuning the system.
They finally released the .45 calibre version of their first radial delayed blowback carbine in April of 2017.
And then they went on to add a bunch more calibres to it.
So 9mm Parabellum is kind of the obvious one, that's I suspect still their most popular, although I don't know.
But then they also added some other cool calibres like 5.7x28, .40 Smith & Wesson, 10mm.
These guys do actually make a 10mm delayed blowback PCC, which is pretty cool.
Not very many people do that.
... When they did the 9mm version that's when they reached out to
MEAN Arms to come up with a version of this magazine for them.
And today they offer this in something like 8 different calibres, as well as a bunch of rifle calibre guns.
So I think this is a really cool example of an innovative system, which is something we don't see all that much these days.
So many things have already been well developed, and well designed, and tweaked,
and fine tuned to the point that ... there's not a lot of room for a lot of new ideas any more.
And this actually is one. So I think it's very cool.
A big thanks to CMMG for sending me this one.
I wanted to go out and try it on the range but I did not want to do it with an arm brace,
so this has been registered as a short- barrelled rifle and it has a proper stock on it.
And tomorrow we are going to take this guy out on the range and do some shooting with it,
and see how it actually handles. So stick around for that.
And thanks for watching.
[ sub by sk cn2 ]