PS Magazine - TB 43-PS-671
PS, The Preventative Maintenance Monthly
ISSUE 671
OCTOBER 2008
20
PS 671
OCT 08
21
PS 671
OCT 08
T
he M2 machine gun now has a side rail adapter that allows you to mount an
additional sight so that you can easily switch from near to far shooting.
A lever on the left side of the adapter lets you easily switch back and forth between
sights.
Check to see if your M2 bracket assembly was manufactured to handle the adapter.
If it has the three pilot holes in the NEAR/FAR adapter, you can order the rail adapter,
NSN 5340-01-536-6189, and install it. See Page 23 in PS 654 for instructions on how
to do that:
T
I
f you apply too much torque when you install the rail kit on the M240B machine
gun, the operating rod can bind in the gas tube.
Do it like this:
Install the two long screws for the rail body and tighten them with your ±ngers.
Then use a
5
/
32
-in hex wrench to tighten the front screw no more than three complete
turns. Tighten the rear screw
1
/
4
turn.
S
mall arms repairmen have had trouble
with the .50-cal mandrel used with the
laser borelight system sliding completely
into the barrel.
As a result, the mandrel’s manufactur-
er has increased the diameter of the man-
drel’s tapered end from .509 inch to .513.
Now the mandrel will stay positioned on
the barrel like it’s supposed to.
Order the new mandrel with NSN 3460-
01-556-9023.
But if your bracket doesn’t
have those three holes, you
will need to order a new
bracket with NSN 5340-01-
502-7233. That will bring
both the bracket and the side
rail adapter.
When mounting the AN/
PEQ-2A sight on the side
rail, use these offsets:
•
500-m zero: IR aim point
•
10 meter-CM:
6.5U, 9.7R CM
•
25 meter-bullet strike zone
in target squares: 2.OD,
9.5L squares
Then function test the weapon. If the op rod binds in the
gas tube, back off both screws
1
/
4
turn. Function test again
and continue to back off the screws
1
/
4
turn until the op rod
moves freely in the gas tube.
MOUNTING
BRACKET FOR
EXTRA SIGHT
M2 Machine Gun…
MOUNTING
BRACKET FOR
EXTRA SIGHT
New Mandrel for LBS
M240B Machine Gun…
Torque
Test for
Rails
New mandrel won’t slip
completely in M2 barrel
ow!
you’ve got
my rail
too
tight.
you need to
back off the
rail screws,
buddy.
I sure could use a second
sight for those times I want
to shoot for distance!
I have just
what you
need…
…a side
rail
adapter!
Check for three pilot holes
Assembled
bracket with
side rail
M2 Machine Gun…
Don’t overtighten!
671.20-21.indd
1-2
9/3/08
1:50:21 PM
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