Personally I wouldn't get a red dot sight for a rifle. I would stick with the iron sights, plus you'd be saving money that way as well. If you absolutely had to buy one, then I would get a pretty darn good one. To me rifles are to be used with iron or fiber optic sights or a scope. In my opinion, red dot sights would be prone to be used on pistols and or shotguns.. That being said, you will aim as per where the shots are registering. Plus you'd be forced to look through a tiny window to find your specified target without any means to zoom in if using it on your rifle. That's just my take on it....by all means you can get the red dot sight to work, just in my experience it's a real kicker =]
Happy shooting,
-Jarred