Discovery Optics ED-PRS GEN II 4-20×52 SFIR FFP-L – Riflescope for PRS Competition and Precision Shooting

The second-generation ED-PRS series from Discovery Optics, the 4-20×52 SFIR FFP-L MRAD variant, is built for shooters who demand a single riflescope that performs equally well on a PRS match stage and in the field on a long-range hunt. The ED-PRS GEN II is not just a list of specifications – it is a tool refined under real-world stress and real shooting conditions.

Japanese ED Glass – the Foundation of Image Quality

At the heart of this riflescope's optical system is Japanese-manufactured ED (Extra-low Dispersion) glass. ED glass minimises chromatic aberration – the phenomenon where different wavelengths of light focus at slightly different points, causing colour fringing at image edges. The result is sharp, high-contrast, true-colour imaging at every magnification level, including at 20× in harsh midday sunlight.

The SFIR lens system features full multi-layer anti-reflective coatings across all surfaces, further improving light transmission and reducing internal reflections. This is particularly noticeable in low-light hunting conditions at dawn and dusk.

First Focal Plane (FFP) Reticle – Accurate at Every Magnification

The FFP reticle layout is one of the most important features of this riflescope. Unlike a second focal plane (SFP) design, the FFP reticle scales proportionally with the image, meaning the MIL subtensions on the reticle remain accurate and valid at every magnification setting. This is a fundamental requirement for PRS competition, and equally valuable for long-range hunting, where mental correction for holdover or wind compensation is simply not an option.

The etched reticle offers 6 levels of red illumination, enabling fast and precise target acquisition in low-light conditions.

Precision Turrets – Lockable with Zero-Stop Function

The 0.1 MRAD click-value turrets offer a total of 35 MRAD of elevation and 17 MRAD of windage adjustment – more than sufficient for extreme long-range work. The turrets feature a zero-stop function: they cannot be dialled below the set zero point, allowing fast and error-free return to base zero. The turrets are also lockable, preventing accidental adjustment during carry or positional shooting.

34mm Tube and 52mm Objective Lens

The 34mm tube is machined from aviation-grade aluminium, providing structural integrity while keeping weight manageable. The 52mm objective lens maximises light gathering, with a noticeable benefit at dawn and dusk.

The side parallax adjustment covers 20 yards to infinity, allowing accurate parallax elimination at both close and extreme long ranges.

Key Technical Specifications

• Magnification — 4–20×
• Objective lens diameter — 52 mm
• Tube diameter — 34 mm
• Focal plane — FFP (first focal plane)
• Reticle — etched, MRAD, illuminated (red, 6 levels)
• Click value — 0.1 MRAD
• Elevation adjustment range — 35 MRAD
• Windage adjustment range — 17 MRAD
• Parallax adjustment — side focus, 20 yards to infinity
• Exit pupil — 2.6–13.3 mm
• Eye relief — approx. 85–87 mm
• Field of view — 1.9 m–9.3 m / 100 m
• Length — 375 mm
• Weight — 1190 g
• Tube material — aviation-grade aluminium
• Nitrogen purged — yes (fogproof)
• Waterproof, shockproof — yes (1500 G)

Who Is This Riflescope For?

The Discovery Optics ED-PRS GEN II 4-20×52 SFIR FFP-L MRAD is primarily recommended for competitive PRS shooters looking for a reliable, FFP, zero-stop riflescope with premium optical quality at a sensible price point. It is equally well suited to long-range hunters working at distances of 300–1000 metres who refuse to compromise on image quality. The 4–20× magnification range makes it versatile enough for mid-range hunting and extended precision work alike. If you have any questions about this product, feel free to contact us – our team is happy to help you make the right choice.

What Users Are Saying

On international shooting forums (Rimfire Central, Long Range Hunting Forum, Airgun Nation), the Discovery Optics ED-PRS series consistently receives praise for outstanding optical performance within its price class. Users frequently highlight the large, easy-to-operate turrets and the surprisingly good image quality, particularly in low-light conditions. One Rimfire Central user summarised their experience by saying that after trying the ED-PRS 5-25×56, they immediately ordered the 4-20×52 as well. Independent reviewer Moondog Industries noted that the 20× version is slightly lighter, shorter, and more affordable than the 25× variant, while offering more than enough magnification for most shooters – especially given that the 12–18× range is the most commonly used in PRS competition.