Instruction Manual EOTECH 553, SU231PEQ Sight | Optics Trade

OPERATOR’S MANUAL
FOR
SU-231/PEQ (HWS M553) (1240-01-533-0941), REFLEX SIGHT, HOLOGRAPHIC, NV
COMPATIBLE, 123 LITHIUM VERSION BATTERY, EOTECH ORDER CODE: 553.A65
HWS M552 (1240-01-492-5264), REFLEX SIGHT, HOLOGRAPHIC, NV COMPATIBLE, AA
VERSION BATTERY, EOTECH ORDER CODE: 552.A65
HWS M551 (1240-01-485-0441), REFLEX SIGHT, HOLOGRAPHIC, NV COMPATIBLE, N
CELL VERSION BATTERY, EOTECH ORDER CODE: 551.A65
See inside cover for distribution statement.
L-3 Eotech Inc. Technical Manual ver. 1.7
JULY 2007
communications
EOTechL3

DISTRIBUTION STATEMENT: Distribution is authorized to U.S. Government
agencies and their contractors. This publication is required for administration and
operational purposes. Additional copies of this document can be found on the
manufactuerʼs website. Written requests must be referred to:
L-3 EOTech Service Dept.
Attn: TM Request
1201 E. Ellsworth Road
Ann Arbor, MI 48108
(734)741-8868 Option #8
general@L-3com.com
DESTRUCTION NOTICE: Destroy the sightʼs operability by removing the battery
cap, batteries, and then crushing the battery cap. Destroy this document by any
method that will prevent disclosure of contents or reconstruction of the document.
This defense article is controlled under the International Traffic in Arms
Regulations (ITAR), and may not be exported to a Foreign Person, either in the U.S.
or abroad, without a license or exemption from the U.S. Department of State.
The 553 is designed to mount only to rail systems that are made to the dimensions
of the current MIL-STD-1913 rail specification. Rails which do not meet the
dimensional requirements of the MIL-STD-1913 specification may result in the
sight fitting loosely, moving on the rail during recoil, or not allow the cam levers to
close properly.

WARNING
WEAPON SAFETY: Prior to mounting the HWS on your weapon, be sure the weapon
is cleared. If you are not sure how to clear your weapon, please see the accompanying
operator’s manual for the weapon platform you are mounting the sight on.
LASER SAFETY: The HWS is a Class II laser product. The Class II level illuminating
beam, however, is completely blocked by the housing. The only laser light accessible
to the eye is the image beam and is at a power level within the limit of a Class IIa laser
product. The illuminating beam can become accessible to the eye if the housing is
broken. Turn the sight off immediately and return the broken unit to the factory for
repair.
FCC COMPLIANCE: The HWS complies with Part 15 of the FCC Rules. Operation is
subject to the following conditions: (1) this device may not cause harmful interference
and (2) this device must accept any interference received, including interference that
may cause undesired operation.

CAUTION
• Never disassemble the sight’s optical assembly. The optical cavity is purged,
nitrogen filled, and sealed to achieve fog proof performance. Disassembly will
void the warranty and render the sight inoperable.
• There is a 12 volt battery that is approximately the same size as the Type N 1.5 volt
alkaline battery used in the M551. DO NOT USE the 12 volt batteries. They will
severely damage the sight.
• When used with a Night Vision device, always check to make sure the sight is off
before pressing the NV button to turn on the sight in the Night Vision mode.
Otherwise, it will toggle to the Normal mode and saturate the image intensifier.
• When a sudden increase in resistance is felt in the elevation or windage adjustment
shafts, the end of the adjustment range has been reached. DO NOT TURN THE
ADJUSTMENTS ANY FARTHER OR SERIOUS DAMAGE MAY OCCUR TO THE
SIGHT.
• Never clean the glass surface with a dry cloth or paper towel; always dampen the
glass surfaces prior to cleaning

• All moving parts of the sight are permanently lubricated. Do not try to lubricate them.
• Do not use deteriorated or corroded batteries. Inspect batteries for rips, tears,
dents, or cuts in the housing. If there is any exposed, internal content of the battery,
it could effect the operation of the sight.
• The SU-231/PEQ (HWS M553) is designed to mount only to rail systems that are
made to the dimensions of the current MIL-STD-1913 rail specification. Rails which
do not meet the dimensional requirements of the MIL-STD-1913 specification may
result in the sight fitting loosely, moving on the rail during recoil, or not allow the cam
levers to close properly.

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TABLE OF CONTENTS
Page
1.0 INTRODUCTION............................................................................................ 1
1.1 General Information...............................................................................1
1.2 Key Attributes ...................................................................................... 2
1.3 Equipment Description ........................................................................ 4
1.4 Location and Description of Major Components ................................. 9
2.0 OPERATING INSTRUCTIONS.......................................................................11
2.1 Description of Components, Controls, and Indicators .........................11
2.1.1 Hood .........................................................................................12
2.1.2 Batteries ...................................................................................12
2.1.3 Replacing Batteries...................................................................14
2.1.4 Electronic Features...................................................................15
2.1.5 Night Vision Mode.....................................................................16
2.1.6 Windage and Elevation Adjustments........................................17
2.2 Preventive Maintenance Checks and Services (PMCS).....................19
2.3 Troubleshooting...................................................................................21
2.4 Unit Level Maintenance and Repair ....................................................24
2.5 Installation of Equipment .....................................................................26
2.6 Zeroing Procedures.............................................................................28

3.0 MOUNTING SOLUTIONS..............................................................................33
3.1 M4/M16 Flat Top Co-witness .....................................................................34
3.2 M4/M16 Adjustable Cantilever Mount ........................................................34
3.3 M4/M16 Fixed Cantilever Mount................................................................35
3.4 M4/M16 Carry Handle Mount.....................................................................36
3.5 HK Low Profile ...........................................................................................37
3.6 HK Mid Profile............................................................................................38
3.7 Tactical Shotgun Mount..............................................................................39
3.8 SIG SG-550 Mount ....................................................................................40
3.9 FN FAL Mount............................................................................................41
3.01 PVS-14 Ring and Mount ............................................................................42
3.02 AK-47 Mount ..............................................................................................43
4.0 APPENDIX A, COMPONENTS OF END ITEM..............................................44
4.1 Basic Issue Items ................................................................................44
4.2 Replacement Items..............................................................................47
5.0 APPENDIX B, FACTORY CONTACTS ..........................................................50

1.0 INTRODUCTION
1.1 General Information
This manual is an overview of the SU-231/PEQ (M553), M552, and the M551
Holographic Weapon Sights (HWS) or Reflex Sight, and will define the basic
operation, features/benefits, and options of this proprietary optical system. The Reflex
Sight is a state of-the-art optical sighting system, employing holographic sighting
technology for small to medium caliber weaponry and launching type platforms. The
Reflex Sight utilizes holographic optics fabrication technology that is used in the
production of advanced heads up display in attack fighter aircraft for targeting, gauge
reading, weapon system verification, etc. L-3 EOTech has miniaturized the
sophisticated sighting heads up display system into a compact and rugged package
for use on small arms and other weapon platforms.
1

1.2 Key Attributes
The SU-231/PEQ (M553), M552, and the M551 reflex sights are lightweight, non-
magnifying, optical sights designed for Close Quarter Battle. They allow very fast
target acquisition and engagement at short ranges while providing aiming capability
out to 300 meters equal to or better than iron sights.
The major combat advantage of the reflex sight is extremely rapid reticle-on-target
acquisition. As quickly as a target is identified, the holographic reticle can be
superimposed on the target. The sight allows operators
to maintain eye contact on the target and to place the
holographic reticle onto the target without shifting focus.
Operators can quickly acquire the target and reticle in the
same focal plane for fast and accurate shot placement.
The reflex sight appears to project the holographic image
of a reticle on the target plane. The sight can be used as
a bright open reticle image or a fine dot which is limited
only by the acuity of the shooter’s eye. The reticle
pattern is parallax free and the holographic heads up display window allows an
undistorted and unrestricted view of the target.
The reflex sight standard reticle is displayed in Figure 1: 65 minute ring with vertical
and horizontal stadia and a one MOA aiming dot.
2
Fig 1:
Standard
Reticle

The reflex sight offers extremely fast target acquisition in Close Quarter Battle (CQB)
using the large ring, and aiming precision in longer range engagements (using the
MOA Dot) without obscuring the target.
Another advantage of the Reflex Sight is the full field of view which allows the operator
better situational awareness. The Reflex Sight employs a true heads up display
(HUD) window that eliminates blind spots and constricted or tunnel vision associated
with scope sights. Controls are inset into the Reflex Sight housing with no protruding
knobs, battery compartments, or rings obscuring the target. Utilizing natural binocular
vision is an advantage of this sighting system, as well as additional threat
identification through increased operator situational awareness and peripheral vision.
The reflex sight can operate in tandem with Generation I – IV+ night vision intensifier
tubes. Operators can see the holographic reticle image with helmet mounted or
weapon mounted night vision devices. The reflex sight is a passive system and emits
no signature from frontal or from a peripheral aspect. While in the NV mode, the sight
is undetectable by opposing force night vision equipment. The HWS can be
positioned behind night vision systems without any “bloom” on the target area.
The primary use of the reflex sight is for the M4A1 carbine and CQBR in Close
Quarters Battle. The reflex sight is not however, limited to carbines. The reflex sight
is currently employed on medium caliber machine guns, grenade launchers and less
than lethal projectile launchers. The sight provides a 1X (no magnification) sight
picture and is not designed as a long range sight system, however, it can be used as
effectively as iron sights on targets to 300 meters. 3

The advantage of the reflex sight is that it provides the operator superior shooting
performance, rapid reticle-on-target acquisition, full field of view and accurate shot
placement. The reflex sight can be naturally employed by all levels of users, from
novice to the most highly trained operator.
1.3 Equipment Description
SU-231/PEQ (M553)
Operation
Optics: Transmission holography – 100% parallax free
Magnification: 1x
Eye Relief: Unlimited
Length/Width/Height: 4.9”x1.8”x2.8”
Weight: 12.3 oz
Temperature: -40 to 150 F
Waterproof: Submersible to 66 ft depth
Sealing: Fogproof internal optics
Color/Finish: Flat Dark Earth (non-reflective black on some small components)
Adjustment (per click): 0.5 MOA (1/2” at 100 yds)
Adjustment Range: +/- 40 MOA travel
Mount: USSOCOM requirements dictated dual quick release throw levers designed
specifically for the Picatinny (MIL-STD-1913) mounting rail:
• Certain commercial variants to the MIL-STD 1913 rail specification may not be compatible
with the SU-231/PEQ (M553) mounting assembly.
4

• The SU-231/PEQ (M553) base consists of (2) ARMS®
throw levers and is only adaptable to
rails that properly accept the ARMS®
design.
Return to Zero: Repeatable to 1 MOA after re-mounting
Heads-Up-Display Window
Optical Surfaces: Anti-glare coating
Window Dimensions: 1.20” x 0.85” (30 x 23mm)
Window Material: Shatter resistant laminate (3/16” thick)
Field of View (100 yds): 30 yds (28m) at a 4” eye relief
Standard Reticle: 65MOA circle with quadrant ticks with 1 MOA aiming dot
Electrical
Brightness Adjustment Range: 110,000: 1 brightest to lowest
Night Vision Brightness Range: 1000: 1 with NV switch engaged
Power Source: 2 x 123 lithium batteries
Battery Life: 1100 continuous hours at nominal setting 12
Brightness Settings: 30 settings with scrolling feature (10 settings for NV use)
Auto Battery Check Indicator: Flashing reticle upon start-up
Auto Shut-down: At 8 hrs- programmable to 4 hrs
5

M552
Operation
Magnification: 1x
Length/Width/Height: 5”x1.8”x2.25” (131x49x60 mm)
Weight: 11.5 oz (326 grams)
Temperature: -40 to 150 F (using AA lithiums); -20 to 140 F (all other battery choices)
Color/Finish: Non reflective black with hard coat finish
Mount: 1” Picatinny (MIL-STD-1913) rail
6

Electrical
Power Source: 2x 1.5V AA batteries (supports lithium, alkaline, or rechargeable)
Battery Life: 1,000 continuous hours (lithium) at nominal setting 12; 600 continuous with
AA alkaline
M551
Operation
Magnification: 1x
Length/Width/Height: 4”x1.8”x2.25” (102x49x60 mm)
Weight: 8.8 oz (250 grams)
Temperature: -20 to 140 F
Color/Finish: Non reflective black with hard coat finish
Mount: Picatinny (MIL-STD-1913) rail
<#
7

Electrical
Power Source: 2x N type 1.5V alkaline batteries (3.0V)
Battery Life: 200 continuous hours at nominal setting 12
8

1.4 Location and Description of Major Components
Fig 2: SU-231/PEQ (M553)
9

Holographic Window - Contains the embedded holographic reticle pattern that forms a virtual
image of the reticle when illuminated by laser light.
Protective Hood - Preassembled, protective hood increases durability of sight housing and
protects the sight from impact damage.
Battery Latch - A cam lever that secures the removable battery compartment to the sight and
prevents water, dirt, or grime from entering the battery housing.
Removable Battery Compartment - Protective housing that contains the power source for the
HWS. The compartment is easily and quickly removed for the replacement of batteries.
Universal Mount - Integrated Picatinny (MIL-STD-1913) compatible rail.
Windage Adjustment - Adjusts the point of impact 1/2 MOA per click in a leftward and rightward
direction.
Elevation Adjustment - Adjusts the point of impact 1/2 MOA per click in an upward and
downward direction.
On/Off, NV Mode, and Brightness Switches - Raised button control interface allows the
operator to perform and adjust user settings for appropriate and preferred conditions.
10

2.0 OPERATING INSTRUCTIONS
This section describes the features and operating instructions of the M551, M552, and
SU-231/PEQ (M553). Please read the instructions carefully before mounting and using the
sight, and always practice proper firearm safety.
The Reflex Sight will include:
• Sight assembly
• 2 x Type N alkaline (M551), AA alkaline batteries (M552), or 123 Lithium batteries (M553)
• 7/64” Hex wrench (M551 and M552 only)
• Knurled Picatinny Bolt (M551 and M552 only)
• Technical Manual
2.1 Description of Components, Controls, and Indicators
The Reflex Sight uses a laser to illuminate a holographic reticle pattern embedded in the heads-
up display window and forms a virtual image of a reticle pattern. The shooter looks through the
heads-up display window and sees a bright red image of a reticle pattern projected onto the
target plane. There is absolutely no light projected onto the target plane. The Reflex Sight has
no magnification.
11

2.1.1 Hood
The Reflex Sight is equipped with a protective hood. This hood is pre-assembled at the factory.
Should your hood require repair or replacement, please contact your unit armorer for repair,
replacement, or turn in to the manufacturer (L-3 EOTech) for repair or replacement.
2.1.2 Batteries
Two (2) commonly available Type N 1.5 volt alkaline, AA 1.5 volt alkaline or 123 Lithium
batteries power your Reflex Sight depending on the model. A set of batteries comes with your
sight. The Reflex Sight is designed to maintain constant brightness at a particular setting as the
batteries drain down. The reticle brightness will not fade gradually as the batteries run down,
but rather, shut down abruptly. The first indication of the batteries draining is the reticle blinking
when the unit is turned on (see Electronic Features 2.1.4). Another indication of low batteries
is the reticle pattern blinking off and on during recoil. With high recoil guns, this can occur
before the battery check indicates low battery condition. If the reticle pattern blinks off and on
during recoil or turns off suddenly, replace the batteries. Please read and follow the battery
replacement and battery check procedures described in this Manual. Alkaline batteries from
different manufacturers are not all constructed the same way. Tests show some brands are
more susceptible to degradation by the shock of recoil. We recommend the use of Eveready
Energizer™ batteries with the Reflex Sight. It is always good practice to replace the batteries
with a fresh set before a mission.
12

CAUTION - There is a 12 volt battery that is approximately the same size as the Type N
1.5 volt alkaline battery used in the M551. DO NOT USE 12 V batteries in the M551. They
will severely damage the sight.
Two AA size batteries power the M552. Two 123 size Lithium batteries power the SU-231/PEQ
(M553). A set of batteries comes with the sight. Lithium AA batteries offer longer life, particularly
at temperatures below freezing. For this reason Lithium AA batteries are recommended for cold
weather operations. However, it should be noted that the battery checking function, which is
based on the characteristics of alkaline batteries, does not operate properly when Lithium AA
batteries are used in the model M552 and may not indicate a low battery condition until very
little battery life is left. The battery checking function of the M553 is designed only for the
123 Lithium battery and will function as described in section 2.1.2.
Figure 3:
Proper battery
Installation
13

14
2.1.3 Replacing Batteries
Remove the battery compartment by lifting up on the locking cam lever and carefully sliding the
battery compartment away and up from the sight housing (Figure 3). After the battery
compartment is removed, slide the batteries out and replace them with a fresh set. The labels
on the bottom of battery compartment show the correct battery orientation. Always make sure
the gasket is free of dirt before the battery compartment is reinstalled or the water-proofing may
be compromised. To reinstall the battery compartment, point the sight towards the ground and
slide battery compartment onto base. Make sure there is enough clearance between the
contact and the batteries to avoid bending the contacts. Hold the battery compartment down
firmly against the base and close the locking cam. Before you push down on cam lever,
make sure the battery compartment sits all the way down and is parallel to the base.
Verify correct battery installation immediately by turning on the sight and checking if the
holographic reticle appears. If the batteries are left in the sight backwards, they will be drained
of their power.
Fig 4: Pushbutton interface

2.1.4 Electronic Features
All electronic controls are via pushbutton switches located at the rear of the unit housing as
shown in Figure 4. To ensure proper operation of the pushbutton switches, press firmly on the
center of the switch.
1. ON/ Auto Battery Check
Pressing the Up or Down Arrow pushbutton switches will turn the sight ON at Level 12. See
item 4 under this section for a description of Auto shutdown. The sight will automatically perform
a battery check every time it is turned on. If the batteries have less than 20% of life left, the sight
will turn on with the reticle image blinking on and off for 5 seconds. If the remaining battery life
is more than 20%, the sight will turn on with a steady reticle pattern. The battery condition can
be checked any time by turning the sight off and back on. The M553 reticle will blink when the
batteries have between 5 and 8 hours of useful life left.
2. OFF
To turn the sight off, simultaneously press both the UP and DOWN arrows. Verify that the sight
is on by looking through the heads-up display window for the reticle.
3. Brightness Adjustment
Pushbutton switches vary the brightness intensity of the holographic reticle pattern. Pressing
and releasing the pushbutton switches moves the brightness level UP or DOWN one (1) step
from the previous setting. Pressing and holding the UP arrow or DOWN arrow switch will
15

change the brightness level up or down continuously in steps. Twenty (20) brightness settings
provide a dynamic range of 110,000:1 from the lowest setting to the highest setting.
4. Auto Shutdown
The Reflex Sight has an auto shutdown feature. If the sight is turned on by pressing the UP button,
it will automatically shut itself OFF 8 hours after the last pushbutton control is used. The sight
will automatically shut OFF after 4 hours if it is turned on by pressing the DOWN button.
2.1.5 Night Vision Mode On/Off Auto Shutdown
The Reflex Sight is compatible with Generation II, III, III+ and IV+ Night Vision Devices. At the
night vision settings, the reticle brightness is low enough that when viewed with a night vision
device, the reticle image does not bloom.
1. ON/ Night Vision Mode and 8 Hour Auto Shut Down
Pressing the NV Button (see Fig. 4) will turn the sight ON in Night Vision Mode. The sight will
turn on at Level 4 and automatically shut off 8 hours after the last pushbutton control is used.
There are 10 brightness settings in NIGHT VISION MODE with a dynamic range of 1000:1.
2. OFF/ Turning Sight OFF
To turn the sight off, press both the UP and DOWN arrows simultaneously. Verify that the sight
shuts off by looking though the heads-up window with the night vision device.
16

3. TOGGLE/ Between Normal and Night Vision Modes
To toggle between NORMAL and NIGHT VISION MODES, press the NV button. When
switching between modes, the sight will remember the last brightness setting. NOTE 3: When
used with a Night Vision device, always check to make sure the sight is not turned on before
pressing the NV button to turn on the sight in the Night Vision mode. Otherwise, it will toggle to
the Normal mode and saturates the image intensifier.
2.1.6 Windage and Elevation Adjustments
Fig 5: Adjustments
17

Your Reflex Sight features click mechanisms for elevation and windage adjustments. The
elevation and windage adjustment are located on the right-hand side of the sight (Figure 2). The
knob towards the front is the windage adjustment and the knob towards the rear is the elevation
adjustment. Both of these adjustment mechanisms are grooved with a slotted screw head and
require the use of a screwdriver, coin, or spent brass to turn. The elevation and windage
adjustments are shown in Figure 5. For both elevation and windage, each click will change the
bullet’s point of impact 1/2 Minute of Angle (MOA), 1/4 inch at 50 yards, or 1/2 inch at 100 yards.
Also, one full rotation of either knob will change the point of impact 10 MOA, 5 inches at 50
yards, or 10 inches at 100 yards. To move the point of impact UP, turn the elevation
adjustment LEFT. To move the point of impact RIGHT, turn the windage adjustment RIGHT.
The Reflex Sight elevation and windage adjustments are factory collimated with the bore of the
rifle parallel to the mounting rail. The sight should be close to mechanical zero when mounted
on a properly installed rail. Do not turn the adjustments before mounting the sight on the
firearm. Be sure to check that the mount and sight are securely mounted after initial firing
18

CAUTION – There are 80 minutes of total windage and elevation (40 minutes in each
direction) in the Reflex Sight. There are 80 1/2 min. clicks of adjustment from optical
center to the limits of windage and elevation adjustment. To establish optical/mechanical
zero, adjust turrets to limit, then return 80 clicks (do this for both the elevation and the
windage). When encountering an increase in resistance in adjustments, the end of the
adjustment range has been reached. DO NOT turn the adjustments any farther, serious
damage may occur to the sight.
2.2 Preventive Maintenance Checks and Services (PMCS)
OPERATOR LEVEL MAINTENANCE
The operator is limited to replacing batteries and cleaning the battery compartment and outer
housing surfaces of the sight.
REPLACING BATTERIES
See the heading ‘Replacing Batteries’ under section Description of Components, Controls, and
Indicators. Do not use deteriorated or corroded batteries. Inspect batteries for rips, tears, or
cuts in the housing. If there is any exposed, internal content of the battery, it could potentially
effect the operation of the sight.
19

OPERATOR CLEANING INSTRUCTIONS
1. The optical system and the window are coated with anti-reflection material. When cleaning
the glass surfaces, first blow away any dirt and dust. Fingerprints and lubricants can be wiped
off with lens tissue or a soft cotton cloth, moistened with lens cleaning fluid or glass cleaner sold
in any camera store. Never clean the glass surface with a dry cloth or paper towel; always
dampen the glass surfaces prior to cleaning.
2. No maintenance is needed on the sight’s surface, except to occasionally wipe off with a soft
cloth. Use only a water-based cleaner such as glass cleaner, ammonia, or soap and water.
Never use any solvent-type cleaner such as alcohol or acetone. Do not use gun cleaner to
clean or lubricate the Reflex Sight.
3. All moving parts of the sight are permanently lubricated. Do not try to lubricate them.
4. Never disassemble the sight’s optical assembly! The optical cavity is purged, nitrogen filled,
and sealed to achieve fog proof performance. Disassembly will void the warranty and
damage the sight.
20

2.3 Troubleshooting
The following section outlines measures the operator can take in the event of the named failure.
Failure: The sight will not power up:
Corrective Action 1: Ensure the batteries are inserted properly according to the
diagram on the bottom of the battery cap.
Corrective Action 2: Replace the batteries with new, unused batteries that contain a
full charge.
Corrective Action 3: Inspect the battery contact points in both the battery cap and on
the sight itself. These contact points are spring loaded and surrounded by a rubber
gasket that may catch the spring. Move the contact points around and ensure they are
at or above the surface of the rubber gasket.
Corrective Action 4: Reset the electronics by removing any source of power for
approximately two minutes. This will allow a capacitor in the electronics housing to
drain of power, resetting the electronics. Reconnect the batteries and operate the sight
as normal.
Corrective Action 5: Check the battery contacts for corrosion or wear. Clean the contacts.
Corrective Action 6: Turn in the sight for unit level maintenance.
21

Failure: The reticle is fuzzy/ has a ‘halo’ effect/ has more than one reticle:
The reticle is naturally pixilated and the outer circle will appear to be made up of many
small dots. The center circle will still be distinguishable as one dot.
Corrective Action 1: Lower the brightness level of the reticle. This fault is generally
caused by the reticle brightness being too high. The reticle is not designed to be so
bright as to block the target.
Corrective Action 2: The reticle is projected onto your target plane. You must focus on
it like you would any other object at that distance. Do NOT focus on the sight housing
like other reflex sights; focus on your target. The outer ring is designed to be a
reference to center, similar to a ghost ring.
Corrective Action 3: If you wear corrective lenses for nearsightedness, you will require
them to see the reticle in focus, as it is projected onto the target plane. If you wear
bifocals or have astigmatism, you may see a distorted reticle.
Corrective Action 4: Check with others who have used the sight, and compare what
you see to ensure it is not your focal acuity prior to turning the sight in for repair.
Corrective Action 5: Turn the sight in for unit level maintenance.
22

Failure: The reticle is flashing/ flashing on and off/ unit turns off during recoil:
Corrective Action 1: This is the low battery indicator. Replace the batteries.
Corrective Action 2: If the batteries are low, a high recoil weapon platform can cause
the reticle to flash on and off, even before the low battery indicator takes effect.
Replace the batteries.
Corrective Action 3: Replace the battery with Energizer brand batteries. These have
proven to be the most effective to withstanding a consistent amount of recoil. Many
brands of batteries deteriorate faster than others and can result in these failures.
Failure: There is a streak in the reticle/ the reticle is dim/ the reticle fades in parts of the window:
Corrective Action 1: Replace the batteries.
Corrective Action 2: Check with others who have used the sight, and compare what
you see to ensure it is not your focal acuity prior to turning the sight in for repair.
Corrective Action 3: Turn in for unit level maintenance.
23

Failure: I am missing a bolt/ have broken a bolt/ have broken a latch:
2.4 Unit Level Maintenance and Repair
The Unit Armorer or individual responsible for unit level maintenance is only authorized to
replace or repair the following items:
– Batteries
– Battery Cap
– Picatinny Bolt - Hex head
– Picatinny Bolt - Knurled Thumb Screw
– 7/64” Hex Wrench
– Protective Hood and Hood Screws
– Technical Manual
Please see Additional Authorized Items in Appendix A for the corresponding NSN numbers for
the above listed components.
24

If the sight has been turned in for unit level maintenance that requires action in addition to the
above mentioned authorized repair or replacement items, the sight will need to be returned to
the manufacturer for the repair.
Contacting the manufacturer for repair:
1. Visit the manufacturer’s website at https://www.L-3com.com/eotech. Click on the Customer
Service Tab in the menu bar and follow the instructions.
2. Call or email L-3 EOTech’s Customer Service Department at the following:
(734) 741-8868 x3688
general@L-3com.com
3. Be sure to leave a name, contact number, return shipping address, and failure description
in the email or on a voice mail. This will allow the manufacturer to generate a Return
Authorization Number (RA#) to include with the sight(s). DO NOT SHIP THE SIGHTS
WITHOUT A RETURN AUTHORIZATION NUMBER (this will severely delay the turn around
time on repair or replacement).
4. If you require, fill out a DD Form 1149 to include with the sight(s) you will return. Include a
reference to the RA#, and a signature line for L-3 EOTech’s Service Department to sign
indicating the receipt of materials. The signed copy will be mailed, faxed, or emailed back to
you upon receipt of the sight(s) for the purposes of accountability.
25

5. If the manufacturing date located on the bottom of the sight is more than two years old, a
fee will be assessed for repair to include the cost of both parts and labor. A purchase order will
be required to process the repair. Please contact L-3 EOTech for an estimate.
Please send the unit postage prepaid, to address listed in Appendix B. Please include your
name, address, telephone number, and a written description of the problem you are
encountering, and also include the RA #. Whenever possible, ship the sight in its original box.
2.5 Installation of Equipment
MOUNTING
The Reflex Sight is equipped with mounting hardware to attach to a MIL-STD-1913 Picatinny
style rail. To achieve the best results and accuracy, the HWS must be mounted properly. The
Picatinny rail needs to be as parallel as possible to the bore to permit the maximum elevation
and windage adjustments. If it is required, it is strongly recommend that the Picatinny rail be
installed by a qualified gunsmith. To mount the sight, please follow these steps.
26

Models M551 and M552:
1. Locate the post and Picatinny clamp on the underside of the sight. Loosen the hex bolt and
the Picatinny locking bar with the hex wrench (7/64”). If using the Knurled Picatinny Bolt, first
remove the hex bolt by completely unscrewing it from the locking bar and replacing it with the
Knurled Picatinny Bolt.
2. Place the bolt within a groove on the top of the Picatinny rail. Individual preference and the
specific firearm determine the optimal positioning to any specific groove on the Picatinny rail.
3. Make sure the bolt is inserted fully into the rail’s groove and push the sight as far forward as
possible. Tighten hex bolt and retainer screw if using the hexbolt. If using the Knurled Picatinny
Bolt, rotate the bolt until resistance is felt. Using a coin, screwdriver, or other type of flat tool,
rotate the bolt head an additional 3/4” turn to fully tighten.
NOTE 1: Loosen bolt just enough to mount and dismount the sight. Do not back bolt out
completely to avoid losing the Picatinny locking hardware.
NOTE 2: A Picatinny rail cannot be installed directly on some weapons. L-3 EOTech sells mount
adapters to provide a standard Picatinny rail for various weapons used in today’s military and
law enforcement applications. Contact a Factory representative if you are unclear on the
mounting adapter you should use on your weapon.
27

Model SU-231/PEQ (M553):
1. Pull and turn the two throw-levers so they are away from their closed and nested position in
the base of the sight. This will turn the securing lip of each throw lever outward and allow the
sight to mount onto the rail.
2. The sight contains a small post that rests in the groove of the Picatinny rail. Move the sight
to the position desired on the rail and allow the post to rest fully in the closest groove.
3. Push the sight as far forward as possible and close both of the throw-lever arms so they are
fully shut and nested in the base of the sight.
2.6 Zeroing Procedures
Once the weapon’s iron sights have been zeroed, please refer to the section on Windage and
Elevation Adjustments (Section 2.1.6) to zero the Reflex Sight. The following are some
additional reference aids that can be used during the zeroing process.
28

BORE SIGHTING
Bore sighting is a good preliminary procedure in achieving proper alignment of your sight to the
firearm. A chamber laser/ bore sighter is an aid in achieving collomation.
LIVE FIRE SIGHTING FOR AN M-4 OR M-16
To employ the aiming dot of the Reflex Sight reticle from 10 to 300 meters, the sight can be
zeroed at 25 meters using a standard M4/M16 military zeroing target. With the dot aimed at
center mass of the target, the sight should be adjusted so the round lands approximately 1 cm
below the point of aim at 25 meters. This method of zeroing ensures hitting a target at 100-200
meters where fine tuning should be conducted.
29

Additionally there are custom targets for 25m zeroing used with the M-4 and M16 (see Figure
6), and for Laser Bore Sighting (see Figure 7). Please visit the manufacturer’s website at
www.L-3com.com/eotech or contact the manufacturer for copies of these targets
Figure 6: M-16/M-4 ZERO TARGET
30

Figure 7: Laser Bore Sight for M4/M16
31

RANGE ESTIMATION WITH UNMAGNIFIED HOLOGRAPHIC WEAPON SIGHT
Range estimation can be done with different portions of the projected reticle, such as the center
dot or the ordinal points. Illustration (Figure 9) of range estimation with the DOT reticle. The
aiming dot will displace a one inch area on the target at 100 yards, two inches at 200 yards,
three inches at 300 etc. At 400 yards, an automatic ballistic compensation is accomplished
simply by placing the aiming dot at the top target’s head. With the heavy bullet loads for the
M-4 A1/ MK 12, the bullet will drop to approximately the center of torso with a 100 meter zero.
Figure 9: Range Estimating with the HWS
32

3.0 MOUNTING SOLUTIONS
There are numerous configurations with which to employ the Reflex Sight. The M552 and M551
Reflex Sight come with an integrated Picatinny MIL-STD-1913 mounting rail adapter that will
mount to any Picatinny style or 1” dovetail type rail (please see section 2.5 Installation of
Equipment).The SU-231/PEQ (M553) mount is specifically designed for the Picatinny
(MIL-STD-1913) mounting rail. Certain commercial variants of the MIL-STD-1913 rail
specification may not be compatible with its mounting assembly. The SU-231/PEQ (M553) base
consists of (2) ARMS®
throw levers and is only adaptable to rails that properly accept the
ARMS®
design
This chapter outlines available options which can be based on the type of weapon platform or
personal preference. Many of the mounting solutions pictured are available directly through the
manufacturer. Please contact the factory if you have any questions regarding configurations,
orders, or availability (please see Appendix B for factory contacts).
NOTE: The Reflex Sight is fully compatible with all Machine Gun Platforms, as well. This
includes the M249 SAW, M240 series, and the M2 series machine guns.
33

3.1 M4/M16 Flat Top Co-witness:
This configuration positions the sight in front of a flip-up rear iron sight. Allows for co-witnessing
and also allows the shooter to maintain cheek-weld (Figure 10).
Figure 10
3.2 M4/M16 Adjustable Cantilever Mount:
Co-witnesses with iron sights and
maintains cheek-weld. The mount has an
adjustable height at the drop or ‘goose-
neck’, forward of the carry handle. The
mount attaches with a nut to carry handle.
Works with fixed-carry handles (Figure 11).
34
Figure 11

3.3 M4/M16 Fixed Cantilever Mount:
Co-witnesses with iron sights and maintains cheek-weld. The cantilever mount attaches with
a finger operated nut to the carry handle. Works with removable carry handles and fixed
(Figure 12).
Figure 12
35

3.4 M4/M16 Carry Handle Mount:
This mount positions the Picatinny rail on top of the carry handle. Maintains access to iron
sights and has extended rail for night vision systems. Works well with gas masks or peripherals
(Figure 13).
Figure 13
36

3.5 HK Low Profile:
Low profile positioned mount for MP5, 33, 53, 91, 93, 94, and G3. Maintains cheek-weld and
supports night vision operation (Figure 14).
Figure 14
37

3.6 HK Mid Profile:
Mid profile positioned mount for MP5, 33, 53, 91, 93, 94, and G3. Maintains access to ghost
rings and supports NV operation (Figure 15).
Figure 15
38

3.7 Tactical Shotgun Mount:
This is a saddle mount that requires no tapping. It is made for a Remington 870, 1100, 11-87.
Other models are available for the Mossberg 500 and Benelli M-1 Super 90 (Figure 16).
Figure 16
39

3.8 Sig SG-550 Mount:
Reflex Sight mounts at a low profile on the weapon’s receiver. No access to iron sights. The rail
mounts under the diopter and bolts to the side of the upper receiver (Figure 17).
Figure 17
40

3.9 FN FAL Mount, Para Version Available:
Reflex Sight is mounted at a low profile. The mount replaces the dust cover. No tapping
required. No access to iron sights (Figure 18).
Figure 18
41

3.10 PVS-14 Ring and Mount:
A mounting platform for the PVS-14 NV system behind the Reflex Sight. Base mounts to
Picatinny rail and ring to NV tube. Ring has QD lever for fast removal. Also available for Litton
983 NV tubes (Figures 19, 20).
Figure 19 Figure 20
42

3.11 AK-47 Mount:
Reflex Sight mounts at low profile. Rail slides over gas tube near rear sight aperture.
AK type/barrel diameter needs to be specified. No access to iron sights (Figure 21).
Figure 21
43

4.0 APPENDIX A: Components of End Item
4.1 BASIC ISSUE ITEMS: M551, M552 ONLY
M551, M552, qty. 1 Part N2075: Picatinny Bolt, hex head; qty 1
(M552 Pictured)
(NSN 5306-01-510-8739)
(M552 NSN 1240-01-492-5264)
(M551 NSN 1240-01-485-0441)
44

Part N2076: Picatinny Bolt, Knurled Part N5800: Hex Wrench, 7/64; qty 1
Thumbscrew; qty. 1
(NSN 5305-01-510-8739) (NSN 5120-01-510-9374)
Part N/A: Military Technical Manual; qty. 1
(NOT PICTURED)
(NSN Not Available, Contact Manufacturer
For Replacement; see Appendix B)
45

BASIC ISSUE ITEMS: SU-231/PEQ (M553) ONLY
SU-231/PEQ (M553), qty. 1
(SU-231/PEQ (M553) NSN 1240-01-533-0941)
46
Part N/A: Military Technical Manual; qty. 1
(NOT PICTURED)
(NSN Not Available, Contact Manufacturer
For Replacement; see Appendix B)

4.2 REPLACEMENT ITEMS (Not All Items Below are Pictured)
Part number Description NSN(for GSA orders)
CR2022 Battery Cap – 123 Lithium Battery Style n/a
N1044 Battery Cap – N style batteries n/a
N1045 Battery Cap – AA batteries 6160-01-510-8734
N2075 Picatinny Bolt – Hex head 5306-01-510-8735
N2076 Picatinny Bolt – Knurled head 5305-01-510-8739
N5252A Retaining Washer, Nylon n/a
N2020 Picatinny Locking Bar n/a
N5800 7/64” Hex wrench 5120-01-510-9374
N2053 Hood For Model 552, 551 1240-01-510-8748
CR2053 Hood For 553 n/a
N1101 Hood Screws (5 screws) n/a
N7752 Type N Battery Set (2 batteries) n/a
CR7751 123 Lithium Batteries (2 batteries) n/a
47

48
Type N Batteries
(1.5v alkaline)
for Model M551
Part N7752
Battery Cap for
Model M551
N Style Batteries
Part N1044
7/64” Hex wrench
for Models M551,
M552
Part N5800
Picatinny Bolt - Hex
head for Models M551,
M552
Part N2075
Battery Cap for
Model M552:
AA Batteries
Part N1045
Picatinny Bolt - knurled
head for Models M551,
M552
Part N2076

49
Hood Kit for
Models M551
and M552
Part N2053
Hood Screws for
all models
(includes 5)
Part N1101
Picatinny
Locking Bar for
Models M551, M552
Part N2020
Nylon retaining
washer for knurled
picatinny bolt
Part N5252A
Hood for Model
SU-231 (M553)
Part CR2053
Battery Cap for Model
SU-231 (lM553):
CR123 Batteries
Part CR2022

5.0 APPENDIX B: Factory Contacts
Customer Service/Repair ....................................................(734) 741-8868 Option #8
Technical Sales/Service .......................................................................(734) 572-2170
Shipping Address:
L-3 EOTech Inc.
1201 E. Ellsworth Road
Ann Arbor, MI 48108
USA
EMAIL........................................................................................general@L-3com.com
Visit us on the web................................................................www.L-3com.com/eotech
OUR PRODUCT IS PROUDLY MANUFACTURED IN THE UNITED STATES OF AMERICA
50

Instruction Manual EOTECH 553, SU231PEQ Sight | Optics Trade

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Instruction Manual EOTECH 553, SU231PEQ Sight | Optics Trade