Overview

The Insight DNS (Day/Night Sight) Model 1800, adopted as the PSQ-18A, is a multifunction aiming device made for the M203 grenade launcher. It works with both 12″ and 9″ barreled versions, and claims to provide increased accuracy compared to conventional ladder/leaf iron sights.

The device provides two means of aiming. A user can make use of the IR Laser and Illuminator, which each have a high and low mode, or use the integrated iron sights. These iron sights are illuminated via tritium inserts, and are made and serviced by Trijicon.

The lasers are activated by means of a single button, placed on the right side. Frankly it is in a quite unusable location and is likely the cause of many complaints. The button can be used in both momentary and continuous modes depending on the sequence of presses.
Later variants required the installation of an PEQ15/ATPIAL compatible tape switch, and had no button.

All models have four active modes, and a conventional blue-backed safety block.
This can be flipped around to “Tactical Mode” (their words not mine) using a .050 hex head allen wrench, which allows the selector to be placed on “DUAL HI”.

History

These devices are part of the 2005 Block 1 SOPMOD M4 Accessory Kit.

According to multiple anecdotes, these devices were not well liked by users. They generally felt that the bulk and weight was not worth the added capability. The M203 DNS was primarily acquired by the USMC and was also used, obviously, by a variety of special operations forces.

These devices had their NSN created on December 26th, 2001.

These were sought to be replaced as early as 2004, per RFQ H92222-04-R-0013. Despite this, the units were in use as late as 2011, and likely later.

In 2013, the PSQ-18 was mostly replaced by the SU-277/PSQ.

Photo by Lance Cpl. Suzanna Lapi, U.S. Marine Corp

Quirks and Features

Cant Detector

The device’s rear LCD displays the currently set range, and battery status. Per the manual, the display’s top section will change from green to a flashing red if it detects that the device is tilted to the side more than 3°.
On my example however (and all others I’ve seen), the bar is not colored.

Illuminated Mechanical Sight

The device has a small green illuminator pointed at the mechanical range readout, which activates when it detects a change in set range.

Adding a rail, and adding to a rail

The device includes provisions for an attached rail to the left side of the device. It can be installed with the rail facing upwards, or to the left. This can be used to add things like an IR strobe, or (yes they actually say this in the manual) an M68 CCO, ACOG, or PEQ-5 CVL. These all seem highly impractical in my mind however.

These devices were eventually made for the M320 standalone launcher, and as such, have direct picatinny mounting solutions. Ensure your model comes with the requisite picatinny adapter if this is what you want. These can be most easily identified by the battery compartment. The M203 version has the battery in-line with the bore, and the M320 version has the battery compartment vertically oriented.

PSQ? And -18 vs -18A

PSQ is the “Joint Electronics Type Designation System” prefix for a “Portable, Special/Combination” device.
Other PSQ examples include the PSQ-42 (ENVG-B), PSQ-20 (Combination NV/Thermal Monocular), and PSQ-36 (Night Vision Binocular Goggles).

The distinction between the -18 and -18A are unclear.

From what I can tell, the NSN for the non-A version was established in 2004, almost three years after the -A version. This does not make much sense, so there might be some issues with the official documentation. As far as the practical differences between models, none could be found.

My best guess is that the -18A was the main, and frankly only model really made. They might have said to themselves “well we aught to add the earlier model to our NSN system even if we never end up having them made, just for continuity”. Both the -A and non-A models can be supplied with mounts for the M203 barrel, so it is unlikely that the -A distinction reflects a difference in M203 vs M320.
If anyone happens to have information on this topic, let me know.

Specifications

WEIGHT AND DIMENSIONS
Weight (with AA Battery)	18.5 ounces
Length	6.5″
Width	4.5″
Height	4.0″
POWER / PERFORMANCE
Range	40 – 400 m
Accuracy	± 5 m
Battery	One AA lithium or alkaline
LASERS
IR Aim Laser
Output Power LOW	500 – 700 µW
Output Power HIGH	2.7 – 3.3 mW
Beam Divergence	0.8 mrad
Wavelength	820 – 850 nm
IR Illuminator
Low Power	2.9 – 3.4 mW
High Power	22.5 – 27.5 mW
Beam Divergence	48 mrad
Wavelength	820 – 850 nm

PSQ-18 NSN:	1015-01-523-7307
PSQ-18A NSN:	1010-01-493-2953

Today, these can be found on the secondhand market for $450-550.
These are all class 3b lasers, and fell off of the back of trucks.