Manual

27
Push the regulator pin all the way in and set the regulator position to the
desired setting. (See Figures 21 - 17, pg. 25.)
4. Pull back the charging handle fully to the rear. The bolt carrier should lock
the bolt open automatically.
STOCK ADJUSTMENT
The SR-556
TM
comes with a 6-position adjustable stock. There are locking
holes on the underside of the extension tube and there is a spring loaded pin
inside the butt stock. To adjust the stock,
squeeze the rear part of the lever on the
underside of the stock against the stock
and slide the entire stock assembly in
toward the lower receiver, or away from
the lower receiver. Release the lever and
move the stock slightly in or out until
the pin snaps into one of the holes on the
extension tube. Try the fit, and if
necessary, readjust the stock. (See Fig.
25.)
QUAD RAIL HANDGUARD
The SR-556
TM
comes standard with a quad rail handguard. This handguard will
accept all attachments designed to fit on a Picatinny or Mil-Spec 1913 rail.
ADJUSTING THE REGULATOR
The SR-556
TM
has an adjustable regulator
which controls the amount of gas that is used to
cycle the piston and in turn the bolt carrier. The
“0” location does not allow any gas into the gas
block and causes the rifle to function as a single
shot rifle. Rounds can be extracted, ejected and a
fresh round loaded by retracting the charging
handle briskly, fully rearward, and releasing it.
(See Fig. 26.) There are three other gas port
settings labeled “1,” “2” and “3” which vary in
size, with “1” the smallest and “3” the largest.
(See Figs. 27 - 29 on page 28.) Use the smallest
gas port setting that reliably cycles the action
with the particular ammunition you are using.
There is no benefit to running the rifle on a gas port setting larger than is
necessary, and doing so may degrade long term endurance.
Most commercial ammunition will cycle optimally on setting “2,” which is an
ideal starting point when first shooting the rifle with new ammunition.
Figure 25
Figure 26