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 ]
This is downright fascinating.
Would there be any advantage to using a similar system with an intermediate cartridge?
I find it hilariously odd that (at least the way Ian tells it) they had to go through this whole process to rediscover such a well established concept as delayed blowback, and that of all the well established, existing delayed blowback guns from which they might have drawn this revelation, it was, of all things, the Reising that actually inspired them.
Still, it's a genuinely novel approach to delayed blowback, and if it works as well as it apparently does, who am I to complain?