My new AR-15 have no sights or scope on it at all right now. I am wanting to get a red-dot for it. It will be used mainly for pinking. It is chambered in .223 & 5.56. I want a cheap red dot, preferably no more than $50, however if I can get cheaper, prefer that Don't have to be anything fancy, but I do want something that will hold up the the round and will not lose center. What would you recommend? Whatever I get must accept a picatinny rail.