Heckler&Koch HK45 COMPACT TACTICAL - Manual (Page 5)

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SECTION 1
Changing/Converting Variants
Due to this innovative design approach unique to some HK pistols, it is
possible to modify an HK45 into any one of the listed variants.
Changing the trigger/firing mode of the pistol is accomplished by installing
a different set of component parts. Not only can the control lever function
(safety/decocking) be switched from one side of the pistol to the other, it is
possible to have a single-action/double-action (SA/DA) version converted to
a double action only (LEM DAO) version, or to any other configuration listed.
Optional ambidextrous controls are available.
This unique design allows the HK45 Pistol to be configured for a variety
of purposes depending on the requirements of the user, without having to
purchase a new pistol.
Special Information on the Law Enforcement Modification (LEM)
The HK45 Pistol received with this manual may be fitted with a special
enhanced Double-Action Only (DAO) Law Enforcement Modification (LEM)
trigger system developed by HK.
The remaining pages of this manual contain information common to all HK45
Pistol models. Many parts of the HK45 are identical for all models, (HK45,
HK45T, HK45C and HK45CT) and the term HK45 applies to all models of this
pistol unless otherwise specified. Please carefully review this material and the
main body of this operator’s manual before handling the firearm.
Law Enforcement Modification (LEM) Description
The LEM is a series of unique trigger parts created specifically to improve the
quality and reduce the weight of the Double-Action Only trigger pull in HK
pistols. With these parts installed, the HK45 Pistol can be fired like a standard
DAO pistol where every round is fired by simply pulling the trigger fully
rearward with the hammer starting at the forward rest position. Generally there
is no external decocking or safety levers present or required, though they are
available as an option.
Due to the design of the proprietary HK LEM, the weight of the DAO trigger
pull has been reduced to 7.5-8.5 pounds when new and is easier to use due to
the smoothness of the trigger pull.
NOTE: An optional 4.5-5.5 pound trigger pull is also available for the HK45
LEM model.
Parts Unique to the Law Enforcement Modification
The unique parts of the Enhanced Trigger System pistol are listed below.
Part numbers can be found on the parts lists contained in this manual or by
contacting HK Customer Service at (706) 568-1906.
Hammer Hammer axle
Cocking piece Hammer strut
Cocking piece spring Trigger rebound spring
Hammer spring Catch
Sear
Operation of the Law Enforcement Modification
HK45 Pistols fitted with LEM parts operate like standard variants of the HK45
Pistol. However, the way in which the hammer is cocked is unique. The hammer
in the LEM is a two-piece hammer comprised of a cocking piece (not visible
with the pistol assembled) and an external (visible) hammer.
The hammer on a conventional Double-Action (DA) or Double Action Only
(DAO) pistol is normally drawn to the rear fully cocked and automatically
released by the relatively long, heavy rearward pull of the trigger by the
operator. To insure reliable primer ignition even under adverse conditions, the
hammer spring that drives the hammer forward is relatively strong.
In a conventional DA or DAO pistol the operator is forced to compress the
hammer spring by squeezing through the entire DA trigger pull while at the
same time trying to hold the sights in alignment for accurate aiming. This can
be difficult especially if the operators hand strength is marginal.
To address this dilemma, HK devised the unique LEM. In the LEM, the quality
of the trigger pull is improved while at the same time a stronger hammer spring
can be employed to improve reliability by increasing the firing pin indent
(strike) on the primer. The stronger hammer spring also helps to reduce the
slide velocity when firing "hot" ammunition thus improving function and reduce
stresses on components of the pistol.
The HK LEM uses the rearward movement of the slide during loading or firing
to fully compress the hammer spring instead of relying on the rearward pull of
the trigger as in conventional DA or DAO systems.
As the slides moves back to the rear, either by the operator chambering the
first round or by the slide recoiling to the rear after ignition of the cartridge,
the bottom of the slide engages and pushes down on the hammer and cocking
piece.
The hammer strut and hammer strut spring are positioned on the bottom
center of the cocking piece. Thus, when the slide passes over the hammer, the
hammer strut is pushed downward and the hammer strut spring is compressed.
Both the hammer and the cocking piece initially rotate on the hammer axle as
the slide moves forward into battery.
HK45 & HK45 Compact