***COUPLE RIFLE QUESTIONS*** just need clarification?

Seems the first thing you haffta do is decide what you're going to do with this rifle. Both .223 & .22-250 are 'varmint' calibers, but the .223 is the most popular by a long way, 'cause of your favorite Uncle Sam. If cheap is the primary factor, then a used gun store should be your place, & take which ever caliber you can find. I consider those two calibers about equal, but, never really got into that area; Smallest I have is a .308/7.62.