Hi guys, thanks for tuning in to another video on ForgottenWeapons.com.
I'm Ian McCollum, if you can see me
behind this forest of Bren guns.
What we are looking at today are the World War Two
wartime simplifications of the Bren gun.
Now I mentioned in our previous video on the original Mark I Bren here,
that the British had produced about 30,000 Bren guns as of May of 1940,
when the Dunkirk evacuations happened.
This of course is the evacuation of the British Expeditionary Force from mainland France,
and it's really kind of one of the darkest parts of World War Two for the British.
Now in the aftermath of this evacuation they go through and realise
they have less than 2,300 Bren guns left in the country
out of 30,000 or so that they had going in.
And this sparks a bit of a panic like,
"What happens if like the Germans manage to disrupt production of more new Bren guns?
We're going to be really screwed."
This is a very important tactical weapon for the infantry company.
So in September of 1940 they formally adopt two separate solutions.
And what had happened is they looked at first off,
"How can we speed up Bren gun production without interrupting it?
Like, what can we implement right now that'll make a Bren gun [faster],
but require basically no setup or infrastructure?"
And so that becomes known as the Mark I Modified Bren.
And it is in effect removal of some lightening cuts and special features,
most significantly, most noticeably, the extra dovetail bracket on the side of the receiver.
But they keep some of the complex stuff like this funky-looking Mark I barrel.
And frankly that only manages to increase production by like 5%.
However it's something they can do without interrupting the continuing supply of new guns.
At the same time they also look at,
"OK, if we start over, what can we do to simplify the gun that would involve retooling?"
And that program becomes the Mark II Bren, which is substantially modified in a lot of ways.
In fact almost every part on the outside of the gun comes out differently on the Mark II.
They leave the internals the same, so the bolt, the bolt components, the operating rod,
bolt carrier, those parts will interchange between all of these different models.
But everything else: the receiver is different, the sights are different, the barrel is different.
And the Mark II Bren kind of takes over into production.
So let's go ahead and take a closer look,
and I'll walk you through the differences between all three of these.
I think the way we're going to do this is we're going to put all three guns together side by side,
and we're going to start at the back and work our way forward.
So throughout the course of this we have our original Mark I here in the back,
we have the Mark I Modified here in the middle, and we have the Mark II in the front.
Important to point out the Mark I Modified,
that "Modified" was never adopted as an actual formal designation.
These simply continued to be marked and referred to as the Mark I.
So on the Mark I Modified guns,
again, this is ... changes we can make without interrupting current production.
So easy enough to get rid of this shoulder stop pad, that goes away.
And they stop equipping them with the bottom handles (which I don't have installed here),
but there was originally a wooden handle for controlling the back end of the gun.
That's superfluous, you really don't need that, so that goes away.
For the Mark II, if we're going to change this up entirely,
you can simplify the design of the buttstock quite a lot.
You can get rid of this hump. The fancy cupped spring-loaded butt plate goes away
in favour of just a simple flat butt plate.
It still has a sling attached to this side, which we'll take a look at in a moment.
Now the sights and receiver. On the modified guns it's easy enough
to get rid of this extra dovetail bracket, that's kind of an obvious thing.
I have a separate video on the sight that went in here, it was really superfluous.
There was also a lightening cut up here at the front of the receiver originally.
That goes away, that's superfluous as well.
And you can see that the lines are substantially simplified here
by getting rid of some of those features.
Once again though, ... if we go to a whole new design of receiver,
a lot of this can be made simpler.
So you can see the complex steps here in the back of the receiver,
if you just make the whole thing a little bit taller you can have more straight lines.
And that's faster and easier to machine.
The [original] drum sight on these guns ... was pretty complex,
like there's a lot of little spring-loaded bits and cams inside there.
And to what end? Do we really need that? This is an outgrowth of the ZB 26.
Well, instead they decide to adopt a much more typical sort of micrometer ladder rear sight.
So you ... now don't need the first dovetail on the receiver either,
so you can make the whole thing flat sided.
And this is a much quicker and simpler sight to make.
So this is the most easily distinguishable visual feature of the Mark II Bren,
this ladder sight in place of the early dial sight.
Moving up towards the front of the gun, there are some rather complex flutes
up here on the front of the original Mark I.
They simplify that substantially here on the Mark I Modified.
And they keep that ... simplified pattern up here.
Really kind of unchanged between the improved Mark I and the Mark II.
We can also see some simplification on this sort of gas shield right here.
It goes from being nicely contoured to being just flat on the Modified Mark I,
and then it simplified even further on the Mark II guns.
Now the other really visually distinguishable difference
between the Mark I and the Mark II is the barrel.
So the Mark I had this stainless steel flash-hider extension on the front.
It was done for good sounding reasons, but ultimately it was not necessary.
And so with this development program they ... produced a whole new pattern of barrel,
this was the Mark II barrel. It gets rid of the stainless steel element entirely.
[A form of] stainless steel continues to be used ... for the gas block right here,
... where it's particularly important to have corrosion resistance.
But the flash hider is built right into the barrel,
the front sight is revised slightly,
it's made a little bigger and beefier, and it's moved forward a bit.
And this is a much cheaper, simpler barrel to make.
In addition, you can see the sleeve for the carry handle is simplified.
Where this was originally a single milled piece with a bunch of fancy lightening holes,
it's now basically solid with the carry handle itself welded on.
Overall, the Mark II Bren would be like a third of a pound heavier than the Mark I,
because most of these simplifications involved not doing extra steps to lighten things.
Just to put this in perspective, the original early Mark I pattern Bren guns
had something like 2,200 machine operations,
and over 1,000 hand fitting operations involved in the production of every individual gun.
So there was a lot to work with to simplify these.
One additional change that unfortunately I don't have here to show you, was to the bipod.
There was a substantially simplified Mark II bipod
that got rid of the spring connection between the legs
and each leg just independently folded.
And of course they got rid of the extendable functionality.
I don't have a Mark II. However, in addition to the Mark I
they also just did a simplified version of the Mark I bipod,
which we do have over here on our Mark II gun.
Where the upper assembly here is the same (right there, that's all the same),
but the legs no longer extend.
And so that's a bit of simplification that was easy to do.
In general, a lot of these parts
were kind of treated independently and individually by British production.
Their emphasis was on getting guns into the hands of soldiers,
not making sure that every gun scrupulously fit a particular set of part designations.
So things like the different bipods on the different models,
different use of the different pattern barrels.
You will see some of that interchangeability in the field.
One other thing that was addressed in the simplification program was, to be honest, reliability.
The Bren gun had performed extremely well in trials.
However, that was done with sort of a basic standardised cleaning and maintenance system
that it turned out wasn't really possible to maintain
on the battlefields in the early months of World War Two.
And British gunners found that without regular cleaning,
the guns tend to build up large amounts of carbon.
Which eventually would actually restrict and then stop operation of the gas piston,
causing the guns to ... basically to stop working
and to become very difficult to clean and get back into service.
Now part of the problem was this series of gas vents that are directly under the bipod.
So the bipod fits onto this spigot.
And having these gas vents, carbon tended to build up on the bipod.
And what you had to do was swivel the gun back and forth on the bipod
to break up the carbon sticking between this and the bipod sleeve.
The problem is over time that would erode the fit
between ... this cylinder and the inside of the bipod sleeve.
And ... once that was no longer a tight fit, gas could escape there,
and it kind of sped up the problems.
Less gas pushing the piston back, and more of it leaking out around the bipod.
So one of the improvements made at this point was a Mark II gas cylinder here
that was solid, got rid of these holes. So it didn't solve all the problems,
at the same time they also enlarged the gas ports to give the guns a little more energy.
As a result of that, the guns tended to be cycling harder, and so the Mark II also has
a double nested set of recoil springs in the buttstock instead of a single spring
in order to absorb the higher bolt velocity as a result of the larger gas ports.
This was kind of a problem that ricocheted down the entire gun,
but that mostly got the problem solved.
Eventually later versions of the gas ... piston assembly here would solve this entirely.
Over on the right side of the gun we can see one other significant change,
and that was to go from the folding charging handle of the Mark I,
to a fixed charging handle of the Mark II.
Now after the war there would be a significant refit and repair program,
and they actually introduced sort of a new designation, a Bren Mark II/1,
in which Mark II guns were modified to allow them to fit folding charging handles.
Because that allowed the gun to be just a little bit narrower in profile,
which was useful for storage, and transportation, and other relatively benign purposes.
And while we're over here, you can also see the change in sling attachment.
The Mark I guns, regular and modified,
had sort of this stud that was used with a snap hook on the sling.
The Mark II was given just a simple standard sling swivel with a plain loop sling.
There were no changes to the markings on the Mark I Modified guns.
However, the Mark II guns were indeed marked "Mark II".
Inglis in Canada did manufacture ... guns to the Mark II specification,
... they started with Mark Is, but they did also build the Mark IIs later on.
And so this is an Inglis marked gun, 1943 dated.
Now there would be one more variation of the Bren gun, and that would be the Mark III.
There was a Mark IV that was trialled, sort of, but never put into production.
Mark III Bren guns are effectively, they're kind of, more or less, a Modified Mark I receiver
with a shortened ... Mark II pattern barrel.
They would produce a lot of those, like 57,000 of those,
but I don't have an example of one here to show you.
So we'll hold off on that until I get access to one for a future video.
Hopefully you enjoyed taking a look at these.
Thanks for watching.