Heckler&Koch VP9 User Manual

Page 6

SECTION 4 FUNCTION AND OPERATION

CYCLE OF OPERATION
The cycle of operation is a reoccurring sequence of mechanical events which takes place

in the operation of a self-loading firearm. The sequence for the VP9 begins with a loaded

magazine inserted into the magazine well with the slide locked back to the rear.

1. Feeding: Removal of a round from the magazine
Depressing either side of the ambidextrous slide release or pulling slightly back on the

charging supports allows the recoil spring to expand, driving the slide forward. The feed

pawl, an extrusion that is located on the bottom of the slide, passes between the feed

lips of the magazine tube, striking the top round and pushing it towards the chamber.

The projectile then contacts the barrel’s feed ramp, allowing the base of the cartridge to

pivot upwards on the slide’s breech face.

2. Chambering: Placing and seating the round into the chamber of the barrel
The recoil spring continues to expand, driving the slide forward and the slide positions

the cartridge into the chamber. The base of the cartridge continues to pivot upwards

as the slide mounted extractor engages the cartridge’s extractor rim. Chambering is

complete by the time the barrel starts to move when the slide comes in contact with the

back of the barrel’s locking block and starts to pivot the barrel upwards and forward.

3. Locking: Closing and locking of the breech mechanism prior to the shot
As the slide is moving forward, the slide’s breech face contacts the extension on the back

of the barrel’s locking block and thus pivots the barrel upward until the stepped forward

edge of the barrel locking block engages the forward edge of ejection port. As the slide

locks into position, the frame mounted disconnector is allowed to pivot upwards into a

corresponding relief cut milled on the inside of the slide, thus allowing the trigger bar

access to sear release catch. The locking phase is complete when the slide reaches its

limit of forward travel.

4. Firing: Ignition of the cartridge’s primer and propellant
As the operator pulls back on the trigger, the trigger safety latch pivots upwards, thus

allowing the trigger to be pulled back towards the rear. The trigger bar, connected to the

trigger moves back as well, allowing an engagement surface on the trigger bar to pivot

the spring loaded firing pin safety to the side which allows the firing pin to move forward

once the trigger is pulled. The trigger bar continues to move to the rear until the back of

the trigger bar contacts and then presses downward on the sear release catch. The sear

release catch, in turn, pushes downward on the catch, disengaging the catch from the

firing pin and then allowing the firing pin to move forward, being driven by the expansion

of the firing pin spring. The tip of the firing pin contacts and then pierces the primer. The

primer detonates which, in turn, ignites the propellant. The projectile, separated from the

cartridge case, is forced down the barrel by the expanding gases and is stabilized by the

polygonal rifling located inside the bore.

5. Unlocking: Removal of any blocking mechanism to allow the opening of the breech
The resultant force of the cartridge firing produces an impact on the slide and barrel,

initially pushing both the slide and barrel back in unison. The slide’s ejection port pushes

back on the barrel locking block and after approximately 4.5 millimeters of travel, pivots

the barrel downward until the barrel’s angular locking surface engages the contact surface

on the frame mounted locking block.

6. Extracting: Removal of the fired cartridge case or live round from the chamber
With the barrel now retained by the locking block, the slide continues to move towards

the rear. The extractor pulls the fired cartridge case or live round from the chamber.

7. Ejecting: Expulsion of the fired cartridge case or live round from the firearm
The extractor engages the cartridge case’s extractor rim as the barrel travels to the rear.

The extractor creates a pivot and the frame mounted ejector creates a contact point, as

the slide rakes the cartridge case against the ejector, allowing the ejector to expel the

cartridge case out through the ejection port.

8. Cocking: Resetting of the trigger mechanism to allow subsequent shots to be fired
In the first few millimeters of rearward travel, the slide passes over the disconnector and

presses it downward, thus precluding the trigger bar from depressing the sear release

catch and immobilizing the firing pin system. As the slide continues to move back towards

the rear, the frame mounted catch engages and pushes back on the lug mounted under-

neath the firing pin, thus compressing the firing pin spring and cocking the firing pin.

SAFETY FEATURES — The VP9 incorporates the following safety features:

1. Firing Pin Safety
The slide mounted firing pin safety helps prevent accidental discharge from impact if

the VP9 is struck or dropped. When at rest, the back of the spring loaded safety pivots

towards the center of the slide and engages a tang that extends downward on the

bottom of the firing pin and thus blocks the firing pin from moving forward in the firing

pin tunnel. Once the trigger is pulled, an engagement surface on the trigger bar pivots

the firing pin safety to the side and allows the forward movement of the firing pin.

2. Trigger Safety
The frame mounted trigger safety also helps prevent accidental discharge if the VP9 is

struck or dropped by blocking the rearward movement of the trigger assembly thereby

immobilizing the trigger bar, unless the entire trigger is pulled back to the rear. With the

trigger bar unable to press downward on the sear release catch, the catch remains upright

and holds the cocked firing pin assembly in place.

3. Disconnector
The frame mounted disconnector ensures that the VP9’s slide must be in battery before

allowing the trigger bar access to disengage the sear release catch and thus preclude the

release of the firing pin. When out of battery, the disconnector is pushed downward by

the slide. In battery, a relief cut milled on the bottom of the slide allows the disconnector

to pivot upwards and allows the trigger bar to travel rewards to disengage the sear

release catch.

4. Disassembly Safety
The disassembly safety ensures that the magazine must be removed from the magazine

well, the chamber be cleared, and the firing pin decocked prior to disassembly. The

dismounting safety is pivoted upwards by the presence of a magazine (loaded or

unloaded) and thus blocks the operation of the disassembly lever. When the magazine is

removed, the dismounting safety pivots downward and allows the disassembly lever to be

rotated forward.

The bottom of the barrel locking block prohibits the operation of the disassembly lever

when the slide is forward. Having to lock the slide to the rear prior to manipulating the

disassembly lever ensues that any round present in the chamber is extracted and ejected.

The activation of the disassembly lever also decocks the firing pin by repositioning the

trigger bar slightly forward. The slide then presses downward on the trigger bar which

disengages the catch from the firing pin.

TIONS FOR USE