Heckler&Koch MR556A1 User Manual

Page 15

Fig. 44 – Loosening the FFRS screw with hex (Allen) wrench

b. Slide the Free Floating Rail System (FFRS) off the barrel nut and remove the FFRS

from the upper receiver.

c. Grasp the rear of the gas piston while pushing back on the piston rod. Disengage

the piston rod from the piston and slide out the piston rod from the upper receiver

(Fig. 45).

Fig. 45 – Removing Piston Rod

d. Slide the gas piston to the rear and remove the gas piston from the gas block (Fig.

46).

Fig. 46 – Removing Gas Piston

5. Lower Receiver:

NOTE: Always ensure the hammer is in the cocked position (down) before attempting

to remove the buffer and action spring.

a. Depress the buffer detent with the tip of the piston rod and remove the buffer and

action spring from the receiver extension (buffer tube) (Fig. 347).

Fig. 47 – Removing Buffer Assembly

b. Check to ensure that the buttstock tightening screw is loose before attempting

to remove the buttstock. If tight, insert the large tip (3mm hex) of the MR556A1

Disassembly Tool into the tightening screw and rotate (but do not completely

remove) counter clockwise (Fig. 48).

Fig. 48 – Buttstock Tightening Screw

c. To remove the buttstock, simultaneously depress the back of the buttstock release

lever while pulling downwards on the front lip. Slide the buttstock off the receiver

extension.

Fig. 49 – Removing Buttstock

The MR556A1 is now operator disassembled (field stripped).

NOTE: Disassembly beyond the above field stripping procedures should only be

undertaken by HK certified personnel.