With their GDO 20 green dot sight, Viridian Weapon’s Technologies has taken their many years of experience with green lasers and applied it to the reflex optic space. A green red-dot optic. It works, and it works great.
The advantage in a green dot over red is that human eyes see green far better than red. They’ve been making green laser devices and a wide range of electro-optics since 2006 based on this simple idea.
However much human eyes “see” green better, there’s no doubt the dot on the GDO 20 absolutely pops.
My astigmatism means there’s no such thing as a crisp dot, but other people tell me the GDO 20 is nice and sharp, and the images taken with my camera show a dot with fairly well defined borders. There’s no halo around the image in full sunlight, no matter how high up you turn the optic’s brightness, and there’s little to no bleeding of the edges either.
If there’s any bluing or false color in the optic, it is very mild. There may be a slight dimming of the image, but if there is, it’s very hard to tell. Looking through the optic as sunset fell here on my Texas Hill Country range, there was no target at 100 yards I could identify without the optic that I couldn’t also identify through the optic.
The GDO 20 isn’t very big. With only a 20mm objective, there’s not a whole lot of real estate inside the optic. Combined with a wide, flat ring around the objective and the emitter housing visible inside the image, you’re not going to get a big view of what’s around your target, especially if it’s in bright light and you turn the 3 MOA dot’s brightness all the way up.
There’s a price to pay for a small, compact 6.2oz form factor, and that price is a bit of situational awareness.
The GDO 20 has eight total brightness settings. Although Viridian advertises them as “7 visible and 1 night vision brightness settings,” they were all visible to me in a dark room.
The night vision setting works well enough. Through my AN/PVS14, the dot on the lowest setting was a little bit too bright in a completely dark room, and there was a definite, but transparent halo effect just around the dot. Still, I wouldn’t have any problems hammering pigs at 100 yards through the GDO 20 in front of NV optics.
If I have one complaint, it’s that maybe they’re right about the whole “eyes see green better” thing. The brightness settings are pretty bright. Even in the brightest daylight, the top two brightness levels were too much. At the Range at Austin’s indoor lanes, I kept hoping for a slightly dimmer setting for precision work, but there was an abrupt dropoff from “a bit too bright” to almost invisible.
There is no auto-brightness level. Brightness is controlled by two simple buttons on the top of the housing. They’re easy enough to manipulate with a bare hand, but they’re a little small and close together to operate with gloves on.
The GDO 20 runs on a single AAA battery (one is supplied) and Viridian’s specs state it will run for 30,000+ hours on a single battery at a middle brightness setting. I have no way to verify that number as that’s over 3 years time, but I can verify that it will sit on this setting or slightly higher for a full three months without being turned off, because that’s what I did.
The included high Picatinny mount attaches with a single nut. This is a bit nit-picky, but Viridian didn’t get this quite right. The nut is slotted so that you can use a large screwdriver or other flat object to tighten the nut down. But once tightened down, the screw portion extends too far into the nut to use the slot.
If you don’t carry a socket into the field, any tightening or loosening of the optic now has to be done with whatever can be found, usually some sort of multi-tool, which mars the nut itself.
I’d like to see a QD mount offered, but the mount included on the GDO 20 works well. Once the nut was appropriately torqued down, it never budged, even under the stoutest recoil. It also sits at the right height to co-witness irons on an AR and should fit well in front of flip-away magnifiers.
I was a bit surprised at the IPX6 waterproof rating for the GDO 20. At this level of waterproofing, there’s very little danger of water damage being a problem, with the exception of prolonged dives in deep water. The actual standard for IPX6 is “can withstand high pressure, heavy sprays of water.” I swished it around in my bathtub and set it on the floor of the shower for a couple of days. Zero issues.
I now have zero concerns about the durability or reliability of the GDO 20. I ran the GDO 20 for part of my Palmetto State Armory AKV9 review and it worked great on that platform. However, the soft-recoiling 9mm AK variant wasn’t much of a test for the optic.
Enter the Taurus Raging Hunter in .460 S&W Magnum (review pending). Even with its obnoxious muzzle brake, there’s no getting around the recoil of a revolver pushing 360gr murder rocks at 1,800 fps (that’s a real chrono’d number).
I used the GDO 20 on top of the Raging Hunter in preparation for an upcoming safari. Despite a whole lot of truly punishing recoil, the GDO 20 never failed in any way. The “recoil management” box has been solidly checked.
The Viridian GDO 20 has a lot to offer. Solid construction, light weight, easy controls, long battery life, a bright image and more from an American company that’s been around a while. It competes in an awfully crowded space, but it competes well.
The GDO 20’s feature set is pretty standard now, although it’s achieving that standard at a lower price than most of the other optics in its class. It’s that green dot on a “red dot” optic that really sets it apart.
Specifications: GDO 20 Green Dot Electro Optic
3 MOA Green Dot
20 mm objective lens
1 MOA windage and elevation turrets
7 Visible & 1 Night Vision Brightness Settings
ACTIVATION: Push-button
MOUNT: Picatinny high mount
BATTERY LIFE: 30,000+ hours (middle setting)
BATTERY TYPE: AAA
OBJECTIVE LENS: 20 mm
TOOLS: Included in packaging
MATERIALS: High-grade aluminum alloy
OP TEMP: -4 °F to 125 °F
WATERPROOF: IPX6
WEIGHT: 6.2oz
WARRANTY: 7 years
COUNTRY OF ORIGIN: Made in China
DOT SIZE:3 MOA
DOT COLOR: Green
OPTICAL ZOOM: 1x
MSRP: $259 (under $230 online)
Rating (out of five stars):
Overall * * * *
The Viridian GD0 20 is a solid performing reflex optic at a very reasonable price. The image is crisp and clear, the battery life is great, and it can take some serious recoil. I wish it were a bit bigger and had an auto-brightness feature, but as it is, this is a heck of a value.
