Heckler&Koch MR762A1 - Manual (Page 18)

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b. Insert the cam pin into the shaft of the bolt carrier, ensuring that the hole for the
firing pin on the cam pin is aligned with the firing pin tunnels on both the bolt head
and bolt carrier (Fig. 59).
Fig. 59 – Bolt Carrier reassembly
c. Ensure that the captive firing pin retaining pin is drifted completely out to the left
hand side of the bolt carrier. Insert the firing pin spring onto the firing pin, pivot
upwards on the spring loaded firing pin safety, and insert the firing pin and spring
into the bolt carrier’s firing pin tunnel until the firing pin reaches its limit of forward
travel (Fig. 60).
Fig. 60 – Installing the Firing Pin
d. While maintaining forward pressure on the back of the firing pin, drift the firing pin
retaining pin from left to right.
e. Ensure that the firing pin retaining pin is properly installed by pivoting upwards on the
firing pin safety while pushing backwards on the bolt head. The firing pin should be
retained inside the bolt carrier (Fig. 61).
Fig. 61 – Firing Pin Retaining Pin Installation
f. Turn the upper receiver upside down, insert the charging handle into the upper
receiver, align the lugs on the outsides of the charging handle with the recesses on the
inside of the upper receiver then press down until the charging handle is flush with the
inside of the receiver then press slightly forward (Fig. 62).
Fig. 62 – Charging Handle Installation
g. With the upper receiver and charging handle upside down, install the bolt assembly
onto the bottom of the charging handle ensuring that the bolt carrier’s anvil and the
top of the cam pin are centered in the bottom cavity of the charging handle (Fig. 63).