Airsoft Scopes and Magnified Optics
There is a specialized role in the game of Airsoft that is as challenging as it is rewarding. That is the role of an Airsoft Sniper or Airsoft Designed Marksman. Both of these use special, accurized Airsoft guns and shoot different ammunition than regular Airsoft Electric Guns. To take full advantage of the more powerful and accurate Airsoft Sniper Rifles or Designated Marksman Rifles (DMR), it would be best to use a Scope that has some sort of Magnification that will allow better precision while aiming at your target as well as better Positive Identification of your target before you fire. These more powerful scopes also allow you to spot your enemies hiding, confirm what you think maybe an Enemy player, and allow engagement with more confidence at a distance that is further than your opponent's gun can reach.
A lot of Airsoft Fields will have special rules for Airsoft Sniper Rifles or Airsoft DMRs. Typically these guns are able to fire at a higher velocity with a minimum engagement distance (MED) and MUST have a Magnified Optic. When shopping for a scope for your Airsoft Sniper Rifle, you can choose a functional scope with a Magnification of 1.5x zoom all the way up to 16x zoom. However, most of your engagements will be at a maximum distance of about 100 yards. While a lot of magnification isn't necessary to engage a target at 100 yards, it does allow you to spot and identify targets beyond that distance and report their movements to your team. Typically these scopes will have a variable magnification so you can dial it down for closer targets, and crank the magnification up for those longer distance targets.
I typically recommend using a scope that has a magnification range of 3x zoom to about 9x zoom. The most popular and common scope is a 3-9x40mm. This means the scope has a 3 to 9x magnification and a 40mm diameter objective lens. They are very common and affordable and provide plenty of zoom for Airsoft and the larger objective lens allows a lot of light transmission for a bright and clear view of your target.
Some of the scopes do offer a parallax error adjustment knob/dial, however, they are typically found on scopes with higher magnification and it does make the scope more expensive. I would say with the practical accuracy of your Airsoft gun, being able to adjust for parallax error is not a mandatory feature. But it is possible to see an error of 2-4 inches at 100 yards.
Q & A:
Q: Do I have to put a magnified optic on my Sniper Rifle or DMR?
A: Absolutely not! You could use a Red-Dot sight. However, most field rules require that you do. Also, you wouldn't be taking advantage of that extra range and accuracy your gun is capable of!
Q: How come the reticle on my scope is blurry or not very clear?
A: Everyone's eyes are slightly different so you need to make some minor adjustments to the scope's eyepiece (Diopter) which is located at the eye-bell of the scope. There is usually a knurled ring that is adjustable. Aim at the sky (not the sun) and crank the diopter until the reticle is blurry. From there while looking through the scope at the sky, keep adjusting the ring until the reticle is razor-sharp.
Q: Do I need anything else to use a scope on my gun?
A: While a lot of scopes come with rings to mount to your gun, some do not. You might also want to look into getting a lens protector to protect your investment. Browse the Mounts and Accessories section.