Usp Pistol Armorers Instruction


The Universal Self-loading Pistol (USP) is the first HK pistol designed for the demanding needs of the American shooter.

It has many features desired by law enforcement, civilian, and military users. Its controls are uniquely American, influenced by such famous and successful designs as the Government Model M1911 pistol. And like the M1911, the USP can be safely carried »cocke.; and locked".

The control lever, a combination safety and aecocking lever, is frame mounted and quickly accessible; unlike the slide mounted safeties common on many pistols. The USP control lever has a positive stop and returns to the "fire" position after decocking.

Using a modified Browning-type action with a special HK recoil reduction svstem(patent pending), the USP is built to take the punishment of the most powerful .40 caliber loads.And unlike most other .40 caliber pistols, the HK USP was designed as a "forty"- it was never "scaled up" from an existing 9mm pistol model.

The polymer frame of the USP was designed using technical experience gained by HK enc.neers in the development of the world's first composite material pistols, the VP70Z and the P9S. This same high-strength/corrosion free material is used in the .45 ACP handgun designed by Heckler & Koch for the US Special Operations Command (USS6C0M) in 1992.

Metal components on the USP are also corrosion resistant. Outside metal surfaces are protected by an extremely hard, nitro-gas carburized black oxide finish. Internal metal parts, including springs,are coated with a special Dow Corning anti-corrosion process that reduces friction"and wear. The HK USP is presently available in calibers .40S&W and 9mm parabellum. Other calibers will be available in the future.

The design characteristics of the USP provide a wide range of flexibility for users. The 9mm model of the US? carries sixteen cartridges, fifteen in the magazine and one in i he chamber. The .40 caliber model holds a total of fourteen .40 cartridges, thirteen in the magazine and one in the chamber.

By using a modular approach to the internal components, the control lever of the USP can be switched from the -left side to the right side of the pistol for left-handed shooters. The USP can also be converted from one type of trigger/firing mode to another. This includes combination double-action and single-action (DA/SA) modes and double action only (DA-only) modes. The USP is available in 10 variants. NOTE: TRIGGER/ FIRING MODE CONVERSIONS CAN ONLY BE MADE BY AN HK ARMORER.

Due to this innovative design approach, it is possible to modify any HK USP into any one of the listed variants.

This unique design allows the USP to be configured for a variety of purposes depending on the requirements of the user, without having to purchase a new pistol.


Browning 380 Pistol


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USP 9mm

Caliber .40 S&W 9 x 19mm Parabellum

Operating Principle Short Recoil

Action Type Modified Browning Type,linkless


Fixed patridge style,


Total length



Barrel length



Sight radius



Twist length




Height(total) 136mm(5.35in)

Width of Slide 29mm(1.14in)

Width of Frame 32mm(1.26in)

Height(total) 136mm(5.35in)

Width of Slide 29mm(1.14in)

Width of Frame 32mm(1.26in)

Weight without magazine 790 grams(27.86 oz) 7S2 grams(26.52oz) Weight of empty magazine 50 grams (1.76 oz) 55 grams (1.94 oz) Slide Force "(to retract slide) 9 kg (19.85 pounds)

Trigger travel(rest to hammer release)

Single-action 6.3mm(.25in)

Double-action 11.3mm(.45in)

Trigger reach (center of trigger to back of frame) Single-action 70mm(2.76in)

Double-action 75mm(2.95in)

Rifling 6 lands and grooves,constant right hand twist

Magazine capacity 13 rounds 15 rounds


Slide - Machined from a solid profile bar of high carbon steel, finished with a Hostile Environment finish

Extractor - Large steel extractor held in by a pin, spring loaded

Barrel locking block - large area on the top of the barrel provides the surface to lock the gun in battery

Front sigh:: - Pressed into a dcve-taii adjustable for elevation by replacement like the P7

Frame - Polymer with steel inserts

Trigger guard - Large to accommodate gloved hands, flared on the bottom to shield the magazine release.

Trigger - located in the trigger guard

Universal mounting grooves - used for the mounting of accessories

Slide release axle - On the right side of the frame used protrudes in a conical hole to aid in the removal of the slide

Used to attach a lanyard to in order to prevent the pistol from being inadvertently dropped during Cavalry charges.

Marked on each side of the frame to be used with the safety/decocker to indicate the position of the lever.

Locks the slide to the rear at the will and pleasure of the shooter and after the last round in the magazine. Also used to release the slide when it is locked back.

Lanyard loop

Reference line -

Slide release


Hits the firing pin to fire the gun. Double action only guns the hammer is bobbed.

Control lever

Frame extension

Finger recesses

Used to determine the condition of the firing mechanism. Safe/fire/decock

Extends below the magazine well in the rear of the frame to act as a guide when inserting a magazine and after the magazine is inserted, it gives the butt of the pistol a clean cosmetic appearance. Also is the location for the lanyard loop insert

Located on either side of the magazine well to allow the magazine to be ripped from the gun in the unlikely case of a stuck magazine.

Ambidextrous magazine release -

One piece magazine release can be activated from either side.

Serial number

Located on a metal insert plate in the bottom of the frame in front of the trigger guard.


Safety check

Point the pistol in a safe direction

Put the control lever in the "safe" position if applicable

Pull the magazine from the pistol

Pull the slide to the rear and lock it back

Physically and visually check the chamber for live ammunition Loading the magazine -

Loading the magazine into the pistol

Operating the control lever Firing the pistol Clearing the pistol -


Field stripping

Remove slide release -

Remove barrel and slide group -

Remove recoil spring and recoil spring guide rod FIELD STRIPPING IS COMPLETE


Cleaning - The USP will function in extremelv adverse conditions and will operate while quite dirty; however, this is not the recommended method of operation. This pistol is responsible for the safety of the operator by its proper function and if it is never cleaned it can't be as reliable as it is when clean. This pistol is NOT self cleaning just as it is not self shooting.

It should therefore be cleaned after every time it is cleaned. If you shoot one round from it, it should be cleaned. After every firing it should be cleaned. CLEAN IS CLEAN This is your standard!

Mineral spirits, drycleaning solvents such as Var-sol, Safety clean #105 NEVER GASOLINE! These are for general cleaning throughout the gun.

Bore cleaners- Hoppe's Nitro Solvent, Shooter's Choice, etc..

Solvents -

Bore brushes - Bronze bristle, copper, brass recommended, nylon okay, stainless steel NEVER EVER!! ! !

Fatches - Soft, absorbent. Have seen toilet paper used successfully, but recommend knit patches. Woven patches leave strings. Southern Bloomers good patches

Lubricants - Break-free, Eze-ox, Slick 50 1-lube, etc...

Preservatives- WD-40 is a preservative not a lubricant

Break-free is good, Balistol,RIG, etc..





Visual checks-

Reporting -

Clean from the chamber end always!!!

Push the brush or the patch through in one stroke.

Brush with solvent Wash brush!!!

Patch dry until clean, repeating brushing if necessary. Wash brush!!!

Lube barrel inside and out to prevent rust. Fouling shots are!

Clean with mineral spirit solvents and brush to remove large deposits of carbon and dirt. Generally Lube throughout

Wipe off the outside and the follower then lube very lightly

The operator should know their gun well enough to know if there is something wrong with it. They should perform a visual inspection of the gun as they are cleaning it.

Encourage your people to report problems, not fear retribution.


There are three commonly accepted operating principles used to operate an auto loading firearm. They are utilization of the kinetic energy transformed as the round is fired. The powder in a modern cartridge is converted in a half dozen milliseconds from a dry powder to expanding gases 900 to 1000 times the volume of the powder. Additionally the pressure of this expanding gas can average 38,000 psi with a peak of over 43,000 psi in a 9mm x 19 cartridge.

This firing causes many things to happen. First, as the gases expand the bullet moves from the case into the barrel and the force required to move the bullet causes an exact force to be exerted in the opposite direction. This will become recoil energy and is the power behind two of the operating principles. Second, the gases behind the bullet are continuing to expand. They push the bullet down the bore imparting spin to the bullet by the inscription of the bullet on the lands and grooves of the bore. These grooves are in the shape of a spiral which makes the bullet turn as it travels down the barrel. It can achieve a rate of spin of almost 80,000 rpm in a 9mm. The expanding gases if vented and applied to pistons or rods can be made to power the mechanism of the auto loader. The M-l, M—14, M-16,Remington 1100, M-60 machine gun, and Desert Eagle are just a few of the gas operated weapons used.

One of the features of the gas operated gun is that the barrel is stationary and that the gas is vented from the barrel forward of the nid point of the barrel. This creates a delay which enables the bullet to leave the muzzle and the pressure to drop to a safe level prior to the action opening.

One method of utilizing the recoil energy is called Blowback and broken into two types, the simple and the delayed. The simple blowback system uses the mass of the bolt to cause the delay necessary for the bullet to leave the muzzle. Uzis,Sterling, Sten, M3 Grease gun, Mac 10, and most small .22 semi pistols are simple blowback. Delayed blowback however instead of using the mass of the bolt incorporates a mechanical disadvantage which must be overcome to unlock the bolt and open the action. In the case of the HK MP5 the disadvantage is caused by the rollers. This style of bolt system enables the bolt to be light. If the G3 used the simple blowback, the bolt would weight 36 lbs.

The MP5 functions through the utilization of the symmetrical transmission of energy. The equal and opposite reaction to the bullet traveling down the bore provides more than enough energy to function the gun.

In the recoil operated system the barrel ana breech, barrel and bolt, barrel and slide remain closed while the mechanism is in recoil until the bullet leave the bore and the pressure drops to a safe level. This is done through timing, but the barrel in a recoil system moves. Examples are numerous as all Browning design pistols are recoil operated. The Browning Hi-Power, M1911A1, Beretta, Smith autos, Glock, Sig and many more to include our own USP.


A reoccurring sequence of mechanical events which take place in the operation of an auto loading firearm.

1. FEEDING - removing a round from the magazine.

As the SLIDE moves forward under the pressure of the expanding recoil spring, the feed pawl in the slide rides between the lips of the magazine stripping a round out of the magazine and feeding it onto the feed ramp and then into the chamber.

2. CHAMBERING - placing the round into the chamber of the barrel and searing it fully.

The slide pushes the round forward into the chamber until the mouth of the cartriaae comes to rest on the end of the chamber.

As the round is in the final stages of chambering the round is held by the extractor so chambering is complete by the time the barrel starts to move when the slide comes in contact with the barrel hood and starts pushing the barrel forward with the slide.

3. LOCXING - closing and locking of the breech mechanism prior to the shot.

The slide, being pushed by the recoil spring, continues to apply pressure to the barrel which cams up on the slide release axle and the barrel breech lifts and locks into the ejection port.

4. FIRING - ignition of the propellant powder

The trigger is pulled and the trigger bar moves forward pulling forward on the bottom of the catch which pivot on the sear axle and lifts the firing pin block in the slide. It also contacts the roll pin on the sear and pulls the sear out of the hammer hook releasing the hammer. The hammer falls and hits the firing pin which hits the primer. The primer detonates, igniting the propellant powder and firing has occurred.

5. UNLOCXING - removal of any blocking mechanism from the breech so the breech can open.

The resultant force of the cartridge firing creates an impact on the face of the slide and the barrel recoils to the rear with the slide. As the slide moves the first few millimeters the angled locking lugs on the bottom of the

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Usp Handgun MechanismPropellant Cone Smokeless Homemade Suppressor Silencer9mm Recoill Sistem

Unlocking barrel contact the angular surface of the recoil spring guide. The resulting impact cause .the barrel to be pulled out of battery with the slide and compresses the buffer spring for the first time.

6. EXTRACTING - removal of the fired cartridge case, or a round from the chamber.

As the bullet is leaving the barrel the slide and barrel are unlocking and the slide continues rearward without the barrel, but the extractor does take the empty case with it.

7. EJECTING - expulsion of the round or fired case from the gun.

The extractor holds the empty case to the face of the slide as it travels to the rear. The extractor creates a pivot and the ejector provides a contact point as the slide rakes the case over the ejector, knocking it out of the ejection port.

8. COCKING - resetting of the trigger mechanism to enable subsequent shots to be fired. NOTE: cocking is NOT complete at this time!!

In the first few millimeters of movement the slide rides over the disconnector and presses it down. This disengages the trigger bar from the hammer and catch. The slide also starts cocking the hammer back. The slide ends its rearward travel with the front inside of the slide impacting the recoil spring guide causing the buffer spring to be compressed again.

The slide travels forward through feeding, chambering, locking, and comes to rest before the shooter can release his finger from the trigger. The disconnector also resets in its slot and the trigger bar pops upward due to the spring and plunger under it.

As the shooter releases his finger the trigger bar is allowed to move forward and at the proper time reengages its access notch in the hammer. The pistol is now ready to fire again.

Usp HammerNomenclature For Usp
Slide,max. rearward position



Barrel - pull it out of the slide

Recoil spring guide rod assembly - roll pin holds buffer spring on the rod. Drive it out and the buffer spring will come off, quickly!

Extractor -

Firing pin

Drive out the roll pin, bottom to top to keep from scarring the pin visibly

Remove the roll pin and the firing pin block can be removed as well as the spring. The firing pin can then be removed out the back of the slide.

Front sight

Drift out either side

Rear sight - Drift out either side


Push out sear axle (left to right) Remove detent plate Remove disconnector

Pull hammer back slightly and remove catch

Lift control lever and remove sear cUpusvx^ (JUJ>ji S&J&J AJLM^rvt (jLVtfy—

Squeeze top and bottom of frame and push out lanyard loop insert pin

Remove lanyard loop insert and hammer spring

Push hammer axle out left to right

Lift out hammer

Lift and remove trigger bar

Turn pistol over and dump hammer strut out of frame

Tap frame and remove trigger bar detent and spring as well as control lever slide and spring

Disengage center tab on sear (flat) spring

Pull sear spring out from top

Push trigger pin out right to left

Remove trigger and trigger rebound spring

Push out magazine release axle

Remove magazine release and spring


Depress magazine locking plate and remove magazine floor plate

Remove magazine follower and spring



Insert follower and spring

Depress spring with locking plate and slide floorplate on from front to rear until locking plate snaps into place


Fit magazine spring onto magazine release and place in frame

Drive axle in place

Fit trigger into frame and insert rebound spring from the top

Push in trigger axle

Holding sear spring with pliers insert into frame

Push down with pliers while depressing two outer spring legs with special tool

Insert trigger bar detent and spring into hole in frame

Insert control lever slide and spring into frame Drop hammer strut into frame

Fit trigger bar onto trigger and rotate into frame

Depress trigger bar and insert hammer axle

Fit hammer into frame and push axle through

Depress control lever slide with punch and install control lever

Press in sear

Fit in catch

Slide in disconnector

Lift sear enough to insert punch left to right through frame

Insert sear axle right to left pushing out punch Fit detent plate into position

From the bottom position strut if necessary and install hammer spring

Fit lanyard loop insert on spring, slide into frame, compress spring and install insert pin


Insert firing pin and spring, notch to the right, firing pin block (solid portion in the 9 to 12 o'clock position) and spring

Hold firing pin depressed as you drive in roll pin

Drive in 3 x 14mm roll pin from the bottom

Install extractor and spring and drive in 3 x 14mm roll pin from the bottom.

Drift in rear sight

Drift in front sight

Fit barrel back into slide

Fit recoil spring onto guide rod and install unit into slide group

Holding recoil spring guide rod assembly carefully, reinstall onto frame

Insert slide release l4K

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