Hi guys, thanks for tuning in to another video on ForgottenWeapons.com.
I'm Ian McCollum, and I am here today at Morphy's
with what can really only be described accurately
as an automatic flashbang dispenser.
This is an HK51, not to be confused with
something that H&K ever actually produced.
The HK51 is a creation specifically for the
American civilian recreational shooting market.
Or so I thought, we'll get to that in just a moment.
First the designation: this comes from H&K's official nomenclature, which they don't use any more,
but for a long time they designated all their guns with a two-digit system.
Where the first digit told you the type of gun, and the second digit told you the calibre.
And under that system 5 indicated a submachine gun, and 1 indicated 7.62 NATO.
So the HK54 was the early name for the MP5, a submachine gun in 9mm.
The HK53 was their super-compact submachine gun-sized rifle in 5.56 NATO,
think of it as equivalent to the AKS-74U, the "Krinkov".
And then following on that, an American gunsmith by the name of Bill Fleming came up with,
"Well, we should make the HK51: that same size, an 8.3 inch barrel, in full-power 7.62 NATO."
Which creates a tremendous amount of noise and flash.
Now, I said this was a creation for the American civilian market,
and perhaps the most surprising thing to me in
doing some research on this gun before I actually started filming it,
was to discover that the stories about the SAS are actually true.
This in fact got its origin with the British SAS and SBS, the Special Boat Service.
They actually contracted for a gun of this configuration,
and they contracted with a British company called FR Ordnance to do it.
FR Ordnance then got Bill Fleming, who was an American gunsmith
who specialised in H&K products, to come up with a way to make this work.
It was used, I don't want to say adopted because it was never formally adopted by the British,
but a number of them were purchased under the designation MC51.
And in fact a couple of them were actually used on operational missions by SAS and SBS.
Now very few of these were actually procured by British special forces,
they were not used very much.
... Both agencies independently did some ... testing on different specialty ammunition
to use with this, which I would assume would involve heavy bullets
to try and get the most possible out of such a short barrel.
And there was also a suppressed version.
Especially if you could come up with a subsonic .308
out of a short barrel for the suppressed version, that would make sense.
Ultimately, British special forces abandoned these
in favour of something slightly more practical, that being the HK53.
So essentially the same gun, but in 5.56.
Now, that leaves what we have on the American market.
Fleming, having developed this for the British but not sold very many of them,
realises there's no reason not to sell this on the American market.
... There are two elements here.
Fleming did a lot of business in making H&K automatic sears, and converting HKs to full-auto,
which could be done up to 1986, and made transferable up until 1986.
And then also doing interesting conversion work on HKs, like this.
So this particular gun has a transferable Fleming auto-sear in it, it is fully automatic.
And then it has also been put into this short .308 conversion.
So let me show you it up close, a little bit.
Normally with a rifle, if I want to get the whole thing in frame I have to at least
put it at an angle, but not with this thing.
So, MP5 front handguard, MP5 collapsing stock.
Well, it's not an MP5, this is an HK91 collapsing stock with the two pins, but you get the idea.
Not a whole lot else on here has to be changed.
That's one of the nice things about H&K's really quite modular system
is ... the receiver is the receiver, it'll accept standard buttstocks,
it'll accept standard fire control groups.
And then just a short barrel, and a short front end to it.
So, standard 20 round magazines, nothing special there.
On this side of the receiver the marking has actually been changed to say "51",
this would have originally been an HK91.
If I get the light just right ...
and right about there you can sort of see it.
You can see that ... the number there was ground down.
So the HK is original, the serial number is unchanged - which is very important legally,
and the designation has been changed from 91 to 51.
I should point out the ones that were done for the British
appear to have been done approximately in 1990.
And they were done on G3 receivers, ... the markings on the British MC51s were never changed.
But because they were German made G3s they have dates on them,
and the couple that I have seen pictures of were both 1990 production.
On the right side here we have all of the original German marks.
So this was an HK91 imported by SACO out of Arlington, calibre .308.
And then Fleming has added his own markings here, which is required
because ... in converting the gun to full-auto he becomes the manufacturer,
and has to add his name, address, and his serial number on there.
So that's why we've got double markings on the receiver there.
To be completely honest, I'm not sure I really have a whole lot else to tell you about this.
It's essentially an MP5 in .308, it's got a full-auto selector pack on it, safe, semi, full-auto.
It's got a collapsing stock, which we can just extend like that.
I mean, what better way to make this perhaps even less comfortable
than to give it a collapsing stock?
But it certainly makes it look cool, I mean man, that's just really slick.
So yeah, that's pretty much all I got.
So what I had initially assumed was just a range toy,
turns out actually was legitimately used by real special operations.
Which, I have to be honest, came as a significant surprise to me,
I did not see that one coming, and yet it did.
So, today this is primarily something that is ... a way to get yourself noticed at a machine gun shoot.
There may be a lot of people there with a lot of really cool guns,
but people are going to notice when someone opens up with an 8 inch barrelled full-auto .308.
And I think that's really its primary purpose,
is that sort of deep belly laugh sort of good time fun.
I recommend double ear protection.
Hopefully you guys enjoyed the video, definitely an unusual one to take a look at.
Thanks for watching.