The LC-40-100 GSO

Ring Sight™ LC-40-100-NVG-GSO is a solid glass reflex collimator sight with integral zeroing. It enables a helicopter gunner to aim at both ground and air targets by day and night with Night Vision Goggles (NVG). For low light and in the dark the graticule is lit by an in-built LED array always in place. The LED array is powered by batteries which can be lithium thionyl chloride (giving an excellent temperature range) or others: the brightness is adjusted by the gunner to suit the conditions. This means that low ambient light can be enhanced when needed and that NVG can be used without affecting their control. The LC-40-100-NVG-RN-DTC is the latest design with improved switches to be used on 20 and 30 mm naval cannons.

One advantage of the Ring Sight is its large aperture, 40 x 30 mm, making it the choice for pintle mounted gun where the firer wants the maximum eye freedom as he moves around the pintle, so the gunner does not have to position his eye precisely (up down, sideways and in and out) unlike conventional optical day and night sights which have limited eye freedom in all these directions.

The sights are used by various countries on a variety of weapons. The sights are also capable of being fitted with Laser Illuminators and Range Finders. The picture above shows the sight with an illuminator the ILL/SIM/40 fitted to the M134. This sight is also used by GIAT on their 20 & 30mm cannons. Its 1 x magnification makes target acquisition and engagement easy, especially from a boat or ship moving with the waves.

NATO Stock numbers

  • Sight complete: 1270-99-333-7927

  • Illuminator Ill/SIM/40: 1270-99-052-1023

  • Illuminator Range Finder: 1240-99-448-6267

Features and benefits

  • Keep Both eyes open when aiming

  • Laser illuminator compatible.

  • NVG compatible.

  • Graticule pattern is illuminated and can be adjusted to different brightness settings.

  • No Misting

  • Solid Glass optic


Aperture (mm)
Angular Aperture, Horizontal
Angular Aperture, Vertical
Length (mm)
Width (mm)
Weight (Kg)
Magnification 1x
Graticule Pattern (fig 3)
No 144