PS Magazine - TB 43-PS-635

PS, The Preventative Maintenance Monthly

ISSUE 635

OCTOBER 2005
PS Magazine - TB 43-PS-635 - Page 10 of 33
PS 635
OCT 05
17
M249 Machine Gun…
Dear Half-Mast,
We've started
using the new short
barrel, NSN 1005-
01-475-4296, on
our M249 machine
guns and we were
wondering if you
need to re-zero the
gun when you switch
to the short barrel?
Also, is it OK to
shoot blanks through
the short barrel?
MSG T.A.
Dear Master Sergeant T.A.,
When you switch to a short barrel, you must re-zero
your M249 by adjusting the front sight only. That allows
you to use the standard and short barrel from then on
without re-zeroing.
The Army doesn't want you to fire blanks through the
short barrel. It's possible blanks fired through the short
barrel increase the unlocking velocity of the bolt when
it leaves the barrel socket. That increased velocity could
damage the receiver's inner rail, which makes the M249
unusable. Use the standard barrel for firing blanks,
along with the M249 BFA, NSN 1005-21-912-8997.
If you've already fired blanks through the short bar-
rel, check the inner rail for cracks. See Page 2-45 in TM
9-1005-201-23&P for directions.
For more info, see TACOM Safety of Use Message 04-005. Contact your TACOM
logistics assistance representative for a copy or TACOM at DSN
793-1918 or
(309) 782-1918 or email:
half.
ma
st
@us.army.mil
PS 635
OCT 05
16
M984A1 HEMTT Wrecker…
Protect Tow Cylinder Lines
If you’ve
fired
blanks,
check left
inner rail
for cracks
you
coming?
I better not.
I’m not supposed
to fire
blanks.
if your
wrecker
already
has
both guards,
you’re
good
to go.
1.
Cut two 24-in pieces of 1/8 x 2-in
angle iron. Order by the foot with
Notch both pieces on one end
2.
Place guards
over lines so they
don’t cover cylin-
der check valves.
The notched
ends butt against
the valves.
3.
Hold the
guards in place
with four loop
clamps,
NSN 4730-00-
908-6294.
Here’s how to
prevent
that:
These retract supply lines
on the wrecker’s tow cylin-
ders take a
real beating
during wrecker operations.
The lines are on the
bottom of the cylin-
ders, where they get
mashed when a towed
truck’s bumper or
hood bumps them.
Eventually, they
leak or burst
during a lift.
hey, I’m going out to the
range to shoot blanks.
1
1
/
2
"
1
1
/
2
"
1
/
2
"
635.16-17(C).qxd
8/27/05
12:18 PM
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