Manual

To adjust the regulator, turn the knurled section by hand. A tool can be inserted

into the cross hole for increased leverage if necessary.

It is important to ensure that the regulator detent locks in the detent in the

regulator so that the gas port in the barrel lines up with the gas port hole in the

regulator.

MAGAZINE INSPECTION AND CARE

Check the magazine frequently. The follower must move freely and have adequate

spring tension so that each cartridge is quickly raised to the feeding position.

To test the spring tension, load one cartridge into the magazine and then firmly

press against the cartridge case. Remove your finger quickly. The cartridge should

instantly and fully move into the feeding position. If it does not, the magazine

should be cleaned. If cleaning does not restore proper spring tension, do not use

the magazine. (NOTE: After testing, remove the test cartridge.)

When cleaning is necessary, use a solvent that will not rust the metal components.

CARE AND CLEANING OF THE REGULATOR

It is necessary to clean the piston, regulator and gas block on a regular basis. This

is the drive system of the SR-556

, and keeping this area clean will provide

years of trouble free service. To clean the piston, regulator and gas block, remove

regulator, regulator detent and piston as described on page 25. Use powder solvent

and a brass brush to clean the piston bore in the gas block. Clean the top of the

barrel below the vent in the bottom of the gas block with powder solvent and a

tooth brush. Clean both the piston and the regulator with powder solvent and a

tooth brush as well.

Reassemble the piston, regulator, and regulator detent as described on pages 26

and 27.

Figure 27

Figure 28

Figure 29

A “late” ejection pattern, in which the brass ejects to the rear of the shooter, may be

modified by increasing the gas port size, turning the regulator to a larger setting.

An “early” ejection pattern, in which the brass ejects to the front of the shooter, may

be modified by reducing the gas port size, turning the regulator to a smaller setting.