Dis-assembling the SCAR lower
receiver
ShootingSight LLC
February 2010
For informational purposes only
Do not attempt
DISCLAIMER
• This lower receiver dis-assembly involves
handling several small parts, including springs,
which are easily broken, or lost.
• Do not attempt this unless you are a
competent gunsmith.
• Fully function check trigger and safety
mechanisms after re-assembly to verify proper
functionality.
Single takedown pin General
Lower is one injection molded part Tab on back of lower holds lower into upper
Insides
• Straight compression
spring for the
hammer.
• Metal plates bent in
next to the hammer
help keep trigger well
cleaner, but also make
it impossible to access
if eg a primer falls in.
Diassembly
• First step is to remove small C-Clip from bolt stop. No, it
is not a joke, you have to disassemble the bolt catch, to
get to the trigger components, starting with tweezers, so
you don’t lose this small clip, otherwise you are screwed.
Remove Bolt Stop Pivot
• Second step is to slide the
bolt catch assembly over
slightly, to expose the bolt
stop pivot pin.
• The bolt stop does not lift
high enough for the
assembly to slide out of
the receiver without
pulling the pivot pin.
• Yes, that is the way FN
designed it, the bolt stop
will not clear over the
receiver frame without
total disassembly.
• This is as high as it goes.
• Use a pin punch to
remove the pivot, remove
the bolt catch, and the
spring.
Remove Bolt Catch Assembly
• Slide bolt catch
assembly
completely out of
the lower receiver.
• Note, there is a
little spacer ring
which replaces a
component from
the full-auto fire
control group. Be
careful not to lose
the thing.
Remove right side steel plate
• With the bolt catch assembly withdrawn, you
can rotate the right side plate up, and slide it
off the spring cross pin.
Remove the safety knob
• With a jeweler’s screwdriver, unscrew the small screw
securing the safety knob, and remove the knob.
• This is not a joke. You need a jeweler’s screwdriver to
disassemble the trigger.
Remove Safety
• Twist and pull and you will work the safety out.
• Note there is a detent and a spring underneath
the safety. Do not lose these.
Remove Left Side Plate
• With the safety removed, you can slide the left
side plate to the rear, till it disengages from the
hammer pin, then rotate it upward to remove.
1.
2.
Remove Hammer Spring
• Grab the guide rod with some needle nose pliers.
• This step is best done after the right side plate is removed,
though order is not critical.
• Remove guide rod from pin in receiver. Pin in receiver will
slide out.
Remove Hammer Pin and Hammer
• Hammer pin is headed, and has to be pushed out to the left.
• The ‘wing’ looking swoop on the hammer is a vestige of full-auto,
and does not play a function in a semi-auto version.
Remove Trigger group
• Trigger pin passes
through trigger
spring, trigger, and
disconnector.
Trigger components
