I used a Trijicon reflex sight out to 300 yards. It's not a scope by any means and if you are looking the scope type accuracy, then buy a scope. The sight has a three minute of angle dot and it's easy to mange out to the 300 yard. At 100 yard I set the target on top of the dot, at 200 yards I set the dot on the target, and at 300 yards I place the dot on top of the target. The accuracy is akin to iron sights. That's fine for me as I rarely used a scope as most all of my shooting was done with iron sights. Now the iron sights are difficult to for me see without glasses but I can see the dot clearly with no problem.
They are great for fast sighting and in the dark I still can see the dot if there is any light at all, even if the front of the lens is obstructed. I should note that my dot sight is provided with fiber optic and tritium so I can still see the dot in total darkness. It you intend to use your gun like a iron sighted gun the dot site will get you by just fine. If you want to shoot egg size targets at 200 yards you will need a scope. Eventually I intend to by an EO Tech and the add-on magnifier. I probably wouldn't use magnifier all that much but I definitely would use the EO Tech.