Heckler&Koch MR762A1-LRP - Manual (Page 6)

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ASSEMBLY GROUPS
Fig. 2 – MR762A1 Major Assembly Groups
1. Charging Handle Assembly
2. Buffer and Recoil Spring
3. Lower Receiver Assembly - contains the buttstock assembly (holds buffer and recoil
spring), pistol grip, selector lever, trigger group, trigger guard, magazine catch/release,
bolt catch/release, magazine well, pivot pin and take down pin.
4. Magazine Assembly (20-round shown)
5. Handguard - Free Floating Rail System
6. Bolt Carrier Assembly
7. Upper Receiver Assembly - contains the forward assist, case deflector, ejection port
cover assembly, gas block, compensator, barrel, gas piston and piston rod.
Fig. 2 – MR762A1 Long Rifle (LEFT & RIGHT views)
Chamber – The chamber is the area where the cartridge is seated and the initial phase of
firing occurs.
Bolt and Carrier Assembly – Provides stripping, chambering, locking, firing, extraction, and
ejection of the cartridges using the recoil spring and projectile propellant gases for power.
These parts are made of the highest quality steel.
Bolt – The bolt locking lugs rotate and lock the barrel and bolt together prior to cartridge
ignition.
Extractor – The extractor grabs the rim of the cartridge case and pulls the case out of the
chamber. The extractor spring and buffer provide constant pressure on the rim until the
case is ejected.
Ejector – The ejector pushes against the cartridge base under constant spring tension
and once the cartridge or case is extracted and clears the front of the ejection port, the
cartridge or case is ejected from the firearm.
Cam Pin – The cam pin allows the bolt to cam inside the bolt carrier, which allows the bolt
to lock into the barrel extension when fully forward and cams to unlock when the carrier is
pulled to the rear.
Firing Pin – The firing pin will strike the primer and initiate the firing sequence once the
trigger is pulled. The firing pin will only protrude through the face of the bolt when the
bolt is fully locked forward.
Drop Safety/Firing Pin Safety – Prevents an accidental discharge in the event of dropping
or jolting the gun.
Firing Pin Retaining Pin – Retains the firing pin in the bolt carrier.
Recoil spring and buffer – The recoil spring provides constant pressure on the bolt carrier
and holds the bolt in a locked forward position. The buffer has tungsten granules that act
as an anti-bounce back mechanism.
Buffer detent – Captures the buffer and spring and when depressed, releases them for
removal.
Hammer – The hammer, when released by the trigger, strikes the firing pin. The hammer
returns when the bolt carrier pushes back under recoil, the hammer makes contact with
the disconnector and will release from the disconnector when the trigger is released. The
hammer remains cocked under spring pressure.
Trigger – The trigger, when squeezed, releases the hammer and returns under spring
tension.
Disconnector – Captures the hammer when it is cocked to the rear and releases the
hammer to the sear when the trigger is released. The disconnector then returns to its
original position under spring tension.