Reddots are for speed on medium sized targets and up. However, that doesn't mean you can't be very accurate with one.
Here's an example. My lightweight Colt AR-15 has a 4moa Aimpoint on it. I was shooting at 50 yards using 75gr TAP (pretty accurate stuff). I tried to go for a couple of good groups. No bags, just elbows on bench. This rifle has a forward pistolgrip. I stuck a 3" Shoot'n'See on the target. At 50 yards, the dot is 2moa. I bracketed the dot inside the Shoot'n'See so that there was a 1" even ring all the way around the reddot. Didn't plan it, just worked out that way. Anyway, shot two groups of 5 rds each. Each had the holes touching. No more than 1" in size. Was closer to 0.75" ...I figure I'm good for 2moa with this dot.
I bring this up because dot size doesn't make for inaccuracy. How you place a reticle or sight on a target is what counts. It's more about point of reference than it is about the size of the dot. Now, had I used a tiny 1" dot as a point of aim, then there is a potential for 1" of error on either side since the reddot is 2" ...I could be covering the 1" target dot, but on the maximum left or max right of the 2" reddot, not in the center.
A lot of people shoot irons very well because they know what to look for or look at. It is a similar principle. Do you ever wonder why some guys can take what looks like very coarse sights and hit so well at distance?
Hard to describe I guess. Same thing if let's say the cross hair wasn't thin, it was as thick as the upper duplex part. If you have a target that allows you to get a point of reference, you can put those thick crosshairs on target the same way over and over, no matter how thick they are.
With a 4moa dot, your point of impact will be somewhere inside that dot. This can be a problem at greater range. Say you want to hit a 3" circle at 200 yards. (I can't even see a 3" circle that far, and I've got slightly better than 20/20) ...but let's say you can. The dot is going to cover about 8" ...
In that respect, is isn't useful. Then again - with no magnification, shooting tiny spots like that is tedious if not impossible for most people. What is a reddot better for? Shooting metal plates. Human sized targets out to 300... etc. Things where you're going for an area hit, rather than a pin-point hit. And where you need to do it quickly without the hassle of having to line up irons. In practical use, you are not going to have a perfect paper target calibrated for the dot size at a given distance so you can make the most of your shot. Also, a dot isn't used for a long range precision. There are better tools. Practical use isn't going to be like my above bench story where I took my sweet old time sitting on a comfy bench to squeeze off a small group.
A lot of people like 2moa dots. I find them too small. 4moa (if you know what you're doing) is a small dot, and is quite capable of doing a lot. More so than what most shooters are capable of. It doesn't sacrifice quick pick-up like the 2moa. It is easier to pick up in a hurry yet offers all the practical accuracy you need. If you need more - then you need magnification. That's just my opinion. A 2moa dot isn't going to make a hit where you would have had a miss. I just don't see it in practical use. At least not for what reddots were intended.
