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M2 - All you want to know


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#1 US Victory Museum

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Posted 30 January 2008 - 08:34 PM

I thought I'd post an additional write-up about the
M2HB (Model 2 Heavy Barrel) Heavy Machine gun .50 cal.
(12.7x99mm)

The weapon photographed is a registered Title II live
machine gun. As the days of 65 cents/shot surplus are
long gone, I find that the gun doesn't get the same
workout as it did in the past. I'm down to my last few
dozen cases of surplus Greek 12.7x99mm two-hundred-and-
seventy-some-odd linked belts. About 11 years ago,
surplus was plentiful and cheap.

Soldiers nicknamed the M2HB Ma Deuce (M-2). I call
it Ma Bell; you know just like the phone company.
I am reminded of their old television ads regarding
something about 'Long Distance' and 'Reaching out to
touch someone.' ;-)

Anyway, this pig is 88 lbs of misery to transport (almost
130 if you include the M3 tripod) Although the cyclical
rate of fire is 550 rounds/min, anything more than 40/min.
in a sustained burst will cause excess throat erosion in
a non-stellite lined barrel and will eventually cause
premature wear necessitating a barrel replacement. If
you're rich, like Uncle Sam, then no-biggie; however, if
you're a working schlub as I am, then that gets a bit
pricey as the days of $200 surplus BBLs are long gone.
A modern barrel will cost over a thousand bucks plus.

Maximum range on a tripod mounted weapon is a little over
4 1/2 miles (7.4 km); however, its effective range is
closer to 1 1/5 miles (1.8 km). The WWII era ground
guns could be fired in Semi-automatic and fully-automatic
modes. The rate of fire in full-auto is slow enough that
a skilled gunner could pop-off single shots in full-auto
without selecting the semi-auto feature.

During WWII there were four basic variants in service.
The M1921 Water Cooled .50 BMG saw service early in the
pacific campaigns. I'm sure everyone has seen the famous
film footage from Wake Is. of the M1921 on the Tora Tora
mount shooting at attacking aircraft. The M2HB was the
standard ground gun. The M2AC was an aircraft mounted
variant that had a higher rate of fire. The slip stream
of an aircraft at altitude enabled a lighter barrel
and a higher rate of fire. The M3 and AN-M2 .50 aircraft
variants had even higher rates of fire. A friend of mine
brought out an M3 to a Hernando, FL machine gun shoot
many years ago and fired it from an anti-aircraft extension
mounted on the M3 ground tripod. It was uncontrollable
and quickly taught us the meaning of fear. At a cyclical
rate of nearly 1,300 rounds/min. if was truly a terror
to fire even short bursts. He has since sold it.

If you're interested in seeing a few extra photos of the
weapon on the M63 Anti-Aircraft mount, then see the attached
link to that topic in this forum.

http://www.usmilitar...showtopic=14361

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#2 US Victory Museum

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Posted 30 January 2008 - 08:35 PM

M2HB

In the photo, you can observe that the critical
screws mounting the bolt retracting assembly to
the receiver have been safety-wired into position.
This is to prevent the weapon from disassembling
itself from the vibration of its firing.

Although the T&E looks similar to that of its
diminutive M1919A4 cousin, they differ in size
and are not interchangeable. Most pintles are
interchangeable.

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#3 US Victory Museum

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Posted 30 January 2008 - 08:36 PM

M2HB

Located between the butterfly trigger is the bolt hold-open
mechanism. Barely visible in the photo is a small arm that
engages this mechanism and holds it in the down position.
While held in this position, the weapon will fire in fully
automatic mode; however, when released, the weapon fires
single shots.

When in automatic mode, cessation of firing results in a
closed bolt with a live cartridge in the barrel. In a hot
gun this can result in a cook-off. When in semi-automatic
mode, cessation of firing results in a live cartridge held
in the T-Slot of the bolt, but with the bolt retracted into
the rear of the receiver negating a potential cook-off.

You can see on the buffer assembly the letters AC. This
is for AC Sparkplug (Today know as AC Delco automotive
parts) which was one of many contractors during WWII.

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#4 US Victory Museum

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Posted 30 January 2008 - 08:37 PM

M2HB

The side plate Trigger Assembly. This is
attached to the left side of the receiver.
It is an accessory and therefore isn't normally
found on all M2HBs. This enables the M2HB
to be fired using the remote trigger mechanism
on the M63 Anti-aircraft mount.

Attached Images

  • M2HB_50__04.jpg


#5 US Victory Museum

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Posted 30 January 2008 - 08:38 PM

M2HB

The M2HB is capable of bilateral firing. That is
to say that the belt can be fed from left to right,
or from right to left. Twin mounts on naval craft
(PT Boats) show two guns side-by-side each being
fed from its open side. Just a quick change of
parts in the feed tray and a quick rotation of that
center part will change the CAM path actuating the
top-cover to feed from the opposite direction.

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#6 US Victory Museum

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Posted 30 January 2008 - 08:39 PM

M2HB

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#7 US Victory Museum

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Posted 30 January 2008 - 08:40 PM

M2HB Spare Barrels.

Each barrel has its own carrying handle. This comes
in very hand for hot barrels. One is equipped with a
flash hider. In my opinion, the regular barrel
produces a minimal flash which looks like an orange
glow as opposed to the strobe light effect that an M4
carbine (M16 14" BBL) generates.

Each 24 rounds burns 1 pound of gunpowder. This is
a lot of heat. The mass of the barrel is used as a
heat sink and is capable of absorbing a great deal of
torture; however, it does so at the sacrifice of barrel
life. When you life is at steak, then you beat on it
like a rented mule and only stop firing when it glows
brighter than the element on your stove top when on
high. At the Knob Creek machine gun shoot, I've seen
quad fifties fired from glowing cherry to nearly yellow-
white. At this point the barrel steel (4130?) becomes
elastic and begins to sag. When you've blown a round
through the side of your barrel, you know you've made
an expensive mistake. (I've seen it.)

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#8 US Victory Museum

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Posted 30 January 2008 - 08:41 PM

A post Korean War Bible written from the
words of the prophet John Moses Browning.

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#9 US Victory Museum

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Posted 30 January 2008 - 08:42 PM

Barrel inspection device.

This handy little device uses a mirror so
one can peer into the barrel from a 90 degree
observation position without lifting the barrel
and sticking it against one's eye. This
minimizes the ability of people to pull the old
charcoal / lipstick on the binocular eye cup
trick on you. ;-)

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#10 US Victory Museum

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Posted 30 January 2008 - 08:43 PM

Flash hider.

It's best to safety wire the nuts on the rear or
you'll be blowing it down range the first time
a projectile doesn't clear the orifice.
(Seen it! Not I.)

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#11 US Victory Museum

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Posted 30 January 2008 - 08:43 PM

WWII era rear sight.

This sight enabled a scope to be mounted in
the dove tail. Not terribly practical.

Carlos Hathcock used a scoped M2HB to snipe
a target in Viet-Nam at 2,500 yards. He
killed the boy with the second shot.

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#12 US Victory Museum

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Posted 30 January 2008 - 08:44 PM

Comparison.

From Left to Right.

30mm Machine Cannon (Modern)
20mm Machine Cannon (Modern)
.50 Cal. BMG (12.7x99mm)
.223 Cal. 5.56x45mm (M16)

The .50 BMG is a scaled up .30-06
in both gun and cartridge.

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  • M2HB_50__13.jpg


#13 US Victory Museum

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Posted 30 January 2008 - 08:45 PM

3:1 AP to Tracer .50 BMG compared
to 7.62x51mm (.308) tracer in a M60
machine gun belt.

The Armor Piercing (AP) has turned
steel cores inside the brass jackets.

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  • M2HB_50__14.jpg


#14 US Victory Museum

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Posted 30 January 2008 - 08:46 PM

I can't remember what this colour combination
code stands for. Usually red or orange indicates
tracer, but I can't recall what silver represents.

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#15 US Victory Museum

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Posted 30 January 2008 - 08:47 PM

These don't exist in this form in the military.

These are 900 grain spotter round projectiles
loaded into full length cases with reduced powder
loads.

A shortened .50 BMG case was used to mimic the
ballistic flight path of the 106mm recoilless
rifles. To spot whether the round would be
on target, the shooter would fire the spotter
rounds and look for the smoke and flash until he
was on target, then he'd let rip with the 106mm
and bring down hell from above.

The military surplussed TONS of spotter rounds for
destruction, but Talon (nasty story here) sold
the pulled components on the open market and even
reloaded pulled components. At the hands of Uncle
Sam and through a little mischief of their own
they are now out of business. But WOW! it was
a great party while things lasted. Uncle wised
up and now demands demilling by means of an
electric furnace. No more mana from heaven.

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#16 US Victory Museum

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Posted 30 January 2008 - 08:48 PM

The Browning M2HB is one of the few guns
capable of killing the shooter, as well as
the intended target. One doesn't operate
an M2HB without a set of timing and head space
gauges. Insufficient timing will result in
premature ignition; excess head space can
blow the top cover off, if you're lucky, or
peal the gun like a banana if you're not so
lucky. (I've seen that too.)

By the way, I've never been in the military.
All this asinine behavior I've observed is
from civilian owners getting complacent.

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#17 US Victory Museum

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Posted 30 January 2008 - 08:49 PM

M7 Linking Machine.

I took a few empties and a few links I had laying around
and set them up to demonstrate the method of linking a belt.

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#18 US Victory Museum

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Posted 30 January 2008 - 08:50 PM

A side-by-side comparison of the M3 tripod (M2HB) vs
the M2 tripod (M1919A4).

I don't recall the weight of either off the top of my
head, but the M3 tripod is a complete load for one man.


--------------------------------------------------------------
LAST IMAGE

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#19 usncollector

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Posted 30 January 2008 - 09:24 PM

What a magnificent piece!! I wonder what it would cost a fellow these days to purchase one of these. I am glad you have taken the time to document it and share it with others.

#20 Steve B.

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Posted 30 January 2008 - 09:38 PM

I know two things:

1. I want one!

2. Semi-autos are $7,000 or more just for the gun. Tripod not included.

#21 rayg

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Posted 31 January 2008 - 03:32 AM

Thanks for posting photos of the gun and the excellent info about it, Ray

#22 WWIIBuff

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Posted 14 October 2019 - 12:03 PM

Very nice and a very informative post.




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