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 very rare Bren gun accessory.
This is a Plessey Fixed Line Sight Mark I.
And this is the reason that the very early Bren guns
had a second dovetail bracket in the receiver.
There were originally plans to also develop a telescopic sight,
or rather a telescopic sight mounting for the Bren, but
those were scrapped before they ever came to fruition.
As far as I know, not even prototypes were actually manufactured.
However, in 1939 they did produce a number of these Fixed Line Sights.
So, let's take a look at how this fits, and what this weird thing actually does.
Mounting this to the gun is really very easy.
The only thing we have here is a little thumb screw that tightens it into place,
you loosen that, and this pulls right off the gun.
That thumb screw, by the way, has a plug in it right there
that locks into that hole to mount it to the gun.
When you are not actually using the sight you have this nice carry pouch for it,
with a pretty hefty solid wooden insert there to keep everything nice and protected.
Now, you have to actually rotate the optic so it's ... what would be pointing in at the gun.
And then this just drops into the case right there.
But mostly we are interested in what this thing actually does.
The thing that this sight is typically compared to, and for obvious reasons,
is the Vickers dial sight which has basically the same optical assembly on the top.
However, these two really are intended for different purposes.
They were both adopted in 1939, interestingly, this is a World War Two deal.
These were not used by the British during World War One.
It has a very similar dovetail bracket,
and in fact the Vickers dial sight will mount onto one of these double dovetail Bren guns.
But it was never intended for that use, it wouldn't have been used that way in the field.
Now the purpose of the dial sight is to basically coordinate indirect fire.
So it has very precise markings here
that allow you to calculate exactly ... how much you are moving the aim of the gun.
And we've got that on ... we've got fine elevation, fine windage adjustment.
This isn't an optical sight in that it's a telescope,
it is more like a surveyor's tool basically.
Looking through this and
I don't know if we can actually do it on camera because of focal issues.
Yeah, I can't get you guys a camera view through that, I apologise.
Basically what you've got in there is a little white triangle on a black background.
It's sort of like an occluded eye gun sight, you can't actually see through it,
but it allows you to ... overlay a triangular pointer onto the landscape.
And so you can use it to set a fixed point of aim,
and then you can calculate exactly where you want to put the gun.
What this is intended to do for the Bren is
much different than the Vickers indirect fire dial sight.
This is ... called a Fixed Line Sight,
and it is basically there to allow you to return to a specific point of aim
when you are using the Bren gun on a tripod.
So this of course comes from very early in the Bren gun's use,
when it was still expected that it was going to replace the Vickers gun in practice
as sort of a mounted sustained fire gun.
And one of the things that you might want to do with it is,
say, set it up on a tripod aimed at a particular area.
Let's say that it's a ... choke point in the enemy lines.
And you know if the enemy attacks, they're going to come through there.
So that's where you want to have the machine gun focused.
Well, you set up the tripod, and you can just use the gun's sights to aim at that point.
Then what you would do is mount your Fixed Line Sight here.
And you would set up an aiming point,
typically you would use this with an aiming lamp,
a signal lamp, that you could then also see at night.
And that aiming lamp, or point, can be anywhere.
And what you would do is set this so that it's aimed, using that little triangular pointer,
directly at your signal lamp or aiming point.
Then you make sure that the tripod doesn't move.
You can take the Bren gun off the tripod and use it on the bipod.
You would, of course, also put this away in its case.
You can go run around with the Bren gun. And as long as the tripod hasn't moved,
you can bring ... the gun back to the tripod, put it on the tripod carefully.
Set this back in it, and by ... leaving this adjusted as it had been, you can aim this at your signal lamp,
and then know that your Bren gun is now aimed at that same point that you set it up for earlier.
This isn't a hugely important thing, like I mean don't get me wrong, that's an important thing to do.
But this is not the sort of task that would be expected of the Bren gun
like, at all, ever, once it actually got into combat.
And so very few of these were initially made,
their ... necessity on the battlefield was pretty minimal,
and so they stopped making them very quickly.
I don't have any numbers on exactly how many were manufactured.
It may well have been many thousands,
the serial numbers for these go up into the mid-20,000 range.
But they may have been destroyed, I suspect, because very few of them survive today.
Something like a couple of dozen are known to survive still.
And on top of this, after Dunkirk, the British put into practice a program of simplifying the Bren
that involved getting rid of the bracket that mounted these sights.
So they were used very little, they weren't particularly necessary,
they were kind of part of the original ...
The Bren's a great gun, but the idea of it replacing the Vickers gun in
practice was misguided, and not particularly realistic.
So, that is the Fixed Line Sight.
I should point out, that name "fixed line" comes from a British definition of basically safety zones.
You have a fixed line for the gun when you set it up with a traverse stop,
so that you don't shoot into areas that you don't want to shoot into.
That's where the name comes from.
So right there that is: Sight Fixed Line Bren .303 Mark I.
Manufacture 1939, "PL" I believe is Plessey, that's the company that manufactured them.
And we have a little acceptance proof stamp there on the bottom of the bracket.
I hope you guys enjoyed the video.
Bren guns with the extra bracket for this sight are quite rare today,
and the sight itself is also extremely rare to find.
So a big thanks to the collector who gave me access to these to film for you.
Hopefully you enjoyed it.
Thanks for watching.