Gemtech MK-9K Installation guide

TM-MK-9K
OPERATION AND MAINTENANCE
OF SOUND SUPPRESSOR
MODEL MK-9K
Before using this suppressor,
be certain you have read and
understand this manual.
Manufactured by
GEMTECH
Div. of Gemini Technologies, Inc.
P.O. Box 140618
Boise, Idaho 83714
ISSUED: March 2015

WARNING 
Because sound suppressed weapons make less
noise than non-suppressed weapons, it is easy to for-
get that they are still firearms. It is of vital importance
to remember that a sound suppressed firearm is just
as dangerous as a non-suppressed one, and the same
safe handling requirements apply.
TM-MK-9K
FIRSTEDITION August 1992
SECONDEDITION August 1993
THIRDEDITION November1994
FOURTHEDITION July1995
FIFTHEDITION July1996
SIXTHEDITION April2005
SEVENTHEDITION March2015
Published by:
ATI Star Press
Antares Technologies, Inc.
P.O. Box 140618
Boise,Idaho 83714
Phone:[phone]
COPYRIGHTNOTICE:
©2015 Gemini Technologies, Inc.
All rights reserved. The contents of this publication may not be reproduced in any
form or by any means in whole or in part without the prior written permission of the
copyright owner.

TM-MK-9K
OPERATIONALMANUALFOR
SOUNDSUPPRESSOR MODEL
MK-9K™(9mm)
Manufacturedby
GEMTECH
Division of Gemini Technologies, Inc.
P.O. Box 140618
Boise, Idaho 83714-0618
Phone: [phone]
FAX: [phone]
GEMTECHPROPRIETARY
This document contains proprietary information of Gemtech and is sub-
mitted to the receiver in confidence. Any reproduction, use and/or dis-
closure of this and/or any portion thereof is expressly prohibited with-
out the express written permission of Gemtech
CONTENTS:
ImportantWarning........................................................................... P. 4
GeneralDescription ........................................................................ P. 4
Mountingon Weapons .................................................................... P. 5
Basic Principles .............................................................................. P. 6
Construction.................................................................................... P. 6
Ammunition Notes .......................................................................... P. 7
RoutineCleaning............................................................................. P. 8
FieldStripping ................................................................................. P. 8
Reassembly .................................................................................... P. 8
Servicingthe Tri-Lock mount........................................................... P. 9
Reassembly .................................................................................. P. 10
Use & Limitations ......................................................................... P. 10
Physical Specifications ................................................................. P. 10
Repair Process instructions .......................................................... P. 10
Warranty Statement ...................................................................... P. 10
Assembly Sketch ......................................................................... P. 11

SOUNDSUPPRESSORMODEL MK-9K P. 4
 WARNING 
Failure to follow installation and maintenance instructions
detailed in this manual can result in potential for serious
injury to the user and damage to the weapon. Firearm sound
suppressors are user attached firearm muzzle devices, and as
sucharesubjecttoimproper attachment unless the proper proce-
dures outlined in this manual are followed.
MANUFACTURER’S DISCLAIMER
The manufacturer is not responsible for improper usage of this
product. This product is potentially dangerous, and as such it is the
user’s responsibility to understand and implement its proper use. If
you do not understand the instructions in this manual, please con-
tact the manufacturer for further clarification.
Congratulations!Youhavejust obtainedtheoriginl, classic9mmmuzzle
suppressor designed for the Heckler & Koch MP5 submachine gun. While
an older design, the MK-9K remains one of the most efficient 9mm subma-
chine gun suppressors available anywhere. Before use, please take a few
momentsto read thisinstructionmanual. It is not designed for and should
never be used on a center fire rifle.
GENERAL DESCRIPTION
The MK-9K suppressor is a coaxial design exhibiting increased effi-
ciency as compared to other suppressors of similar external size and ap-
pearance.It is designedtomount ontheH&K MP5 submachinegun utilizing
theHK 3-lugbarrel.On specialorderit canbe provided tomount ona1/2x28
threaded barrel. Suppression efficiency is gained through proper design of
the suppressor rather than by using “wipes” or other obstacles touching the
bullet in free flight. For this reason, weapon accuracy is not impaired, and
accuracy may be actually slightly enhanced by tightening of the group size.
 WARNING 
Failureto followmounting instructionsdetailed inthis manual
can result in potential for serious injury to the user and damage
to the weapon.

SOUNDSUPPRESSORMODEL MK-9K P. 5
MOUNTING ON WEAPONS
Although some versions of the HK MP5 submachine gun have muzzle
threads, we suggest utilizing the 3-lug mount whenever possible, as it is a
superior and more stable mount. For mounting on other weapons, the sup-
pressor can be special ordered to mount on a 1/2-28 threaded barrel.
TheMK-9K using theTri-Lock 3-lug couplermustnever bemountedon
a3-lug threadedbarrelwithout athread protectorinplace. Failureto observe
this caution may result in misalignment. If there is any question, we can
providea suitablethread protector.
Whenmountingon athreadedbarrel,thesuppressor shouldbescrewed
on hand tight only. It is important to periodically ascertain that the suppres-
sor has not unscrewed, which can cause misalignment.
Weguarantee alignmentofthe MK-9Ksuppressoronly onoriginalGer-
man 3-lug H&K MP5 barrels, those converted by S&HArms Co., or on non-
3-lug barrels converted by us. Damage caused by misalignment is not cov-
eredunder the warranty.
 DANGER 


Before performing any installation or maintenance operation,
always remove the magazine from the firearm, open the action, and
visually ascertain that the chamber is empty and the weapon unloaded.
Failure to do so can result in potential for serious injury to the user and
others in the vicinity.
GEMTECH TRI-LOCK MOUNTING INSTRUCTIONS
1.Be certain theweaponis unloaded,themagazine removed, thesafety on,
and the bolt locked in the open position.
2.Align the grooves in the silencer mount with the lugs on the barrel.
3. Pull the silencer onto the barrel against spring tension until the silencer
can be rotated counter clockwise while holding the weapon in the firing
position.
4. Rotate the silencer 60° until it stops and release pressure on the silencer.
Rock the silencer to be certain that the lugs have engaged the pocket
recesses in the mount.
5. Removal is the reverse of installation. It will be necessary to pull the si-
lencer rearward in order to rotate it 60° clockwise.

SOUNDSUPPRESSORMODEL MK-9K P. 6
SINGLE POINT (THREAD) MOUNTING INSTRUCTIONS
1.Be certainthat theweaponis unloaded,the magazineremoved,the safety
on, and the bolt locked in the open position.
2. Screw the suppressor onto the barrel threads, being careful to not cross-
threadthe suppressor.
3. Tighten firmly hand tight. We advocate the use of Blue Loctite to inhibit
unscrewingduring firing.
4.Because silencers using singlepointthread mounting will unscrewduring
use, it is the shooter’s responsibility to frequently check to be cer-
tain that the suppressor remains tightly screwed on the barrel at
intervals not to exceed 1 magazine.
5.We cannot guarantee alignmenton barrels not threadedorgauged by us.
We deny liability for injury or damage caused by misalignment or un-
screwingofthe suppressor.
BASIC SUPPRESSION PRINCIPLES
Thesound of afirearmdischarging is duetothe sudden releaseofhigh
pressurepropelling gases. Thepurpose of asuppressoris toreducethe gas
pressure by a combination of increasing the volume for gas expansion, de-
creasing gas temperatures, and delaying gas exit from the suppressor.
The MK-9K suppressor is a coaxial design unit, consisting of three
suppressionchambers:theinner rearentrancechamber,theinnerfrontcham-
ber, andtheouter coaxialchamber.Theinner rear chamberdiverts pressure
into the outer chamber, offering an exceptionally large volume for initial gas
pressure reduction, trapping, cooling, and exit delay. The baffle stack (cen-
tral core) consists of a steep cone (with a notch in the apex) and a series of
precisionformed stainlesssteel baffles.Stainlesssteel wasusedfor durabil-
ity and resistance to gas erosion and corrosion. The baffles are optimally
spacedfor maximum gas trapping,coolingand delayed gas releaseintothe
atmosphere.
CONSTRUCTION
Theentire suppressor is constructedfrom hard anodized aircraftgrade
aluminum alloys with the exception of the baffles in the central core, which
are precision formed from type 18-8 stainless steel for wear resistance and
durability. No packing materials or consumable parts are utilized.
The suppressor can be partially disassembled for cleaning and routine
maintenance. No tools are necessary for this procedure.

SOUNDSUPPRESSORMODEL MK-9K P. 7
AMMUNITION NOTES
 WARNING  
Never use ammunition that does not meet SAAMI specifications.
AllcommercialAmericanmadeSAAMIspecificationammunitionis safe,
but the origins, storage history, and reason for being surplussed of foreign
madeammunition is notavailable for evaluation.Although foreignmade am-
munition is usually safe, this is not always the case. Damage from non-
Americanammunition cannot becoveredunder warranty.
Themajority of 9mm ammunition issupersonic, and the projectiletrav-
eling at velocities above 1,100 fps will produce a ballistic “crack” or “sonic
boom”. There are several commercial sources of specially loaded subsonic
9mm ammunition, and for maximum effectiveness, we suggest the use of
this type ammunition. Although special 9mm subsonic ammunition has a
bullet muzzle velocity below 1,100 fps, the higher bullet weight results in a
significantly higher bullet kinetic energy.
The majority of subsonic 9mm ammunition is loaded utilizing bullet
weightsof 147grainor heavier.Subsonic ammunitionutilizing bullet weights
of 155 grain or more is apt to be significantly overpressured in some weap-
ons,especially the HKMP5.147 grainFMJand JHP bulletsfor9mm reload-
ingareavailablefromavariety ofsuppliers, includingHornady andSpeer. Do
not use cast lead bullets.Loading data for 9mm subsonic ammunition is
available from a number of sources, including the Speer Supplement (avail-
ablefrom Speerfor their 147grainTMCbullets),andfromAccurateArms for
use with their powders. However, we caution against any attempt to hand
load beyond recommended SAAMI specifications.
Commercial subsonic ammunition is available in 158 grain FMJ from
Israeli Military Industries and in 147 grain bullet weight from Winchester,
Remington, Federal, CCI, and others in both full metal jacket and hollow
pointstyles. We havefound that althoughthis ammunition remainssubsonic
in pistols, it may not remain subsonic in the longer barrel of the Heckler &
Koch MP5 submachine gun. The user will need to experiment with different
brands. Ammunition with bullet weights over 154 grains is discouraged by
H&K. Although some have suggested that the 9mm subsonic cartridge is
“downloaded,” we believe users should be aware that this ammunition is
anything but an anemic load with kinetic energies and pressures signifi-
cantly greater than standard 9mm ball ammunition.
Useof corrosive ammunition, andevidenceof its use, willvoidthe war-
ranty.

SOUNDSUPPRESSORMODEL MK-9K P. 8
ROUTINE CLEANING
Ourexperience suggests thattotaldisassembly for cleaningisnot nec-
essary, and for this reason the inner core is sealed to maintain optimum
positioning of the parts. Field stripping and cleaning should be performed
every2,000 rounds.Becauseof moltenleadsplattering fromtheheat gener-
ated by friction with cast bullets and bullet lubricants, ammunition loaded
with cast lead bullets should never be used.
Afterfield stripping, some cleaningcanbe performed byimmersingthe
central core of the suppressor in a suitable solvent.
Cleaningof thecentralcore isoptional andconsistsprimarily offlushing
out unburned or partially burned powder residues. There are no perfect sol-
vents for the carbon deposited on the internal parts by the burning of the
powder. We have found, however, that Varsol automotive parts cleaner or a
mixture of 3 parts mineral spirits and 1 part TypeA Automatic Transmission
Fluid are among the better solvents for suppressor cleaning. We suggest
against the use of water-based solvents. Never use solvents containing
ammonia,whichcandamagealuminumparts.ThisincludesHoppe’s,Sweets,
and “GI” bore cleaner. Never use water or water-based solvents, which
can damage aluminum. Ultrasonic cleaners have limited value, because
theyrequire water-basedsolvents.
 CAUTION 
Alwaysread the warninglabel on anycleaneror solvent,and
rememberthatvirtuallyallsolventsareinherentlydangerousandpo-
tentiallytoxic.Alwaysuse adequate ventilationandboth skin and eye
protectionwhen using organic solvents.
FIELD STRIPPING (Partial Disassembly)
Unscrewthe frontendcap, whichis threadedintothe centralcore ofthe
suppressor.Thiswill release theoutertube, which is heldincompression by
thefront endcap andrear mount.Asmallneoprene “O”ring inagrooveinthe
rear mount provides a gas seal. Remove the outer tube.
Unscrew the rear mount from the central core. Do not attempt to disas-
semble the central core. At this point the suppressor can be cleaned by
immersion.
Althoughcomplete disassembly of thecentralcoreis theoretically pos-
sible, we feel that so doing is not necessary and is without merit.
Werecommend against theuseof anywaterbased solvent orcleaning
materials.

SOUNDSUPPRESSORMODEL MK-9K P. 9
SERVICING THE 3-LUG MOUNT
The Raptor™3-lug mount can be easily disassembled for servicing.
1. Unscrew the knurled cap from the body.
2. Removethespring-loadedpistonfromthemountbody.Removethespring.
Service consists of:
1. Replacethe O-rings if necessary.The O-ringinthe body can beremoved
with a dental pick. O-rings are Viton (neoprene must not be used).
2. Thoroughly clean the spring-loaded piston inside and out. Made of stain-
less steel, it can be cleaned with red Scotchbrite or fine steel wool moist-
enedwith WD-40.
3. Coat the outside of the piston with grease as well as the inside of the
knurled cap. Lightly coat the inside of the mount body. Suitable greases
include marine bearing grease, available at stores that sell boat trailers.
4.Insert the spring inthemount body followedbythe piston (smallendfirst).
Replace the cap and screw hand tight. Do not use thread adhesives.
It is not unusual for a small amount of grease to be forced through the
small vent hole in the knurled cap. This hole is to prevent pressurization of
the mount.

SOUNDSUPPRESSORMODEL MK-9K P. 10
REASSEMBLY
Reassembly is the reverse of disassembly. When reassembling the
suppressor, we suggest use of a thread lubricant and anti-seize compound,
suchas aTefloncompound oroneof themanyquality commercialanti-seize
materials.
Theholes inthe wall ofcentral corearein therear section. Aftercoating
the threads with anti-sieze compound, screw the rear mount hand tight into
the rear of the central core.
Becertain that the Viton“O” ring in therearmount is intact,andreplace
ifworn orbroken. Replacementsare availableat mostwellstockedhardware
stores or stores selling hydraulic tools and are 1-3/4" x 1/16".
Coat the inside of the end of the outer tube with either a lithium based
grease or Vaseline in order to facilitate disassembly and reduce binding of
the“O” ring. Replace theoutertube and screw inthefront end cap tosecure
all parts in place. This completes the reassembly.
NOTES ON USE
Use of this suppressor on a centerfire rifle will exceed the design pa-
rameters,leading tostructuralfailure ofthe suppressor andpossible injuryto
the user.
Because of the design of this suppressor, heating of the outer tube
duringfully automatic fire is minimized.Iffiring the weapon causestheouter
tubeto heattothe pointofbeing toohotto touch,then the suppressorshould
beallowed tocooluntil it canbe handled withoutdiscomfort before resuming
fire.Because of thisindicationof overheating, wesuggestagainst the useof
aprotective Nomexcover.
PHYSICAL SPECIFICATIONS
Caliber 9mmParabellum (only)
Length 7.5 inch (191 mm)
Diameter 2 inch (51 mm)
Weight 20ounce (570 gm)
LIMITED WARRANTY STATEMENT
Gemini Technologies, Inc., dba Gemtech, warrants to the initial retail
purchaser that Gemtech products will be free of defects in workmanship or
material and that the product meets manufacturing specifications at the
timeofmanufacture.Thiswarranty is limited to the repair or replacement of
theproduct. This express limitedwarrantyis exclusive andnoother express
orimpliedwarranty is otherwise provided.
GEMTECHMAKES NOWARRANTYOF MERCHANTABILITYOR
FITNESS FOR PARTICULAR PURPOSE.
Product technical specifications and/or designs may be changed
without notice. This warranty does not cover negligence, misuse, careless
orimproperhandling and/or operation, abuse, unauthorizedadjustmentsor

SOUNDSUPPRESSORMODEL MK-9K P. 11
modifications, improper mounting/installation, ordinary wear and tear, the
failuretofollow manufacturer instructions and/or the use ofinappropriateor
defectiveammunition.
Gemtech shall have no liability for incidental or consequential
damages and under no circumstances will Gemtech be liable for
personal injury, property damage or economic loss.
This warranty and disclaimer is subject to all applicable laws some of
which may limit these terms.
WARRANTY REPAIRS: Return of a Damaged Suppressor
If a suppressor is damaged due to a manufacturing defect once it has been
fired, it may be returned to Gemtech for repair or replacement. Determination to
repair or replace is made solely at our discretion and only after we have had the
opportunity to examine and determine that the cause of the damage is due to a
manufacturing defect. It is the responsibility of the customer to cover shipping
costs and insurance to return the suppressor to Gemtech for inspection or repair.
Gemtech will pay any reasonable shipping and insurance costs to return the unit
to you.
To assure proper legal procedures for any repair returns, fill out and provide a
copy of the General Service Form with any packages sent to us. (Visit gem-
tech.com, navigate to Customer Support/Return and Repair Policies to download
the fillable General Service Form.pdf or call 208.939.7222)
BATFE no longer requires transfer on a Form 5 to the manufacturer for repair.
BATFE does require a letter accompanying the suppressor detailing the repairs
or modifications required (satisfied by a completely filled out General Service
Form). BATFE also requires proof of ownership satisfied by a photocopy of the
front of the owner’s Form 3, 4, or 5.
NOTE: BATFE prohibits transferring the serial number to a new outer tube in
the case of damage to the tube. Tube damage rendering the suppressor unsafe
will require a new suppressor.

All Gemtech products are
100% manufactured in the
United States of America.