The UK’s best rifle shooting magazine, written by leading experts
GPO are known for packing incredible features into small, compact, and versatile optics. Chris Parkin tests the GPO Spectra 3-15x56i riflescope.
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GPO continue to concentrate on cleanly designed optics with accessible hunting specifications ideal for the daylight and evening hunter in the UK. The Spectra is a 5x zoom range scope running from 3-15x magnification based in a cleanly machined, smoothly matt anodised 30mm aluminium maintube. The 56mm objective lens offers the best balance for low-light hunting situations in terms of light entry to the lens packages without excessive bulk on a scope with an overall length of 360mm. The 830g weight hints at the mass of quality, multicoated glassware GPO use in their optics to give an official ISO-rated light transmission figure of 90%. Eye relief of 95mm is ideal for most sporting rifles with medium to firm recoil, with a plentiful 45/64mm of linear tube space ahead of and behind the central saddle for mounting to your rifle.
Windage and elevation dials give 10mm at 100m clicks, corresponding precisely to 0.1mrad ballistic calculations. The collars carry plentiful knurling for tactile contact, with distinct clicks allowing precise adjustment without needing to see, although the dials are still neatly laser-engraved with 60 clicks per rotation, amounting to 250 clicks total travel.
The outer edge of each dial unscrews, allowing the identification collar to lift off and reset to mark zero. Parallax on the left side runs from 10m to infinity for full rifle type/range versatility, and operates smoothly without backlash for optical clarity. There’s also a fast-focus eyepiece at the rear to correct for your natural eyesight, showing the G4i reticle with the illuminated central dot in sharp contrast. The dot shows linear adjustment in eight analogue stages and has an auto-off function to save CR2032 battery power.
I used the scope on a .243 review rifle and found it to be a good example of the regularly encountered 3-15x format, giving fractionally more versatility at close ranges or on moving quarry than a 4x minimum optic. The scope is finished to the highest standards, with an additional throw-lever to control magnification if preferred. Rubberised lens caps are supplied to protect the optic, and I found all external adjustments controlling the internal erector tube and lens packages for parallax and zoom adjustment smooth running with no internal motion perceptible.
GPO scopes show excellent poor-light performance in their price bracket and I specifically enjoyed the rich colour balance, with flat focal field of view spanning 11.1-2.3m at 100m, with true edge-to-edge clarity. No visual imbalance showed at the ocular lens, and a forgiving eye box makes it easy to maintain target contact throughout the shot/recoil pulse in a hunting scenario.
Tube Diameter: 30mm
Eye relief: 95mm
Exit Pupil: 9.5-3.7mm
Light Transmission: 90%
Click Value: 1cm@100m
Parallax: 100m to infinity
Overall Mechanical range: 250 cm @100m windage and elevation
Accessories: Magnification throw lever, rubberised lens caps, instruction manual, lens cloth, cr2032 battery
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