You know , I have no idea which red-dot is what . They all look the same but have different disciptions . This one says you can use it on shotguns up to 3" shells . http://www.amazon.com/Tasco-30mm-Rif...=tasco+BKRD+30
Shotguns have a heck of alot more recoil then an AR .
This one says the same but is almost 10mm bigger in diameter which should give you a bigger field of view http://www.amazon.com/Tasco-Red-Dot-...=tasco+BKRD+30
The cool thing IMO about lower end products is you can always put them on one of your other guns ( 22s , shotgun ). Thats what I do .
I've got to tell you though . A 5 MOA dot is pretty big . That will cover up a 5" area of your target at 100 yards . If your shooting at something like a squirrel or some other small animal like that . You may not even see it behind the dot . I don't want to be discouraging cus all the lower end red-dots have a big dot . I just wanted to point that out to you .