My wife has decided she wants to varmint hunt with me in the spring, and I am thinkin about using an AR style upper with a bull barrell for her. I have a M&P15, and am not sure which upper to go with. Also, would I be better to go with a 22-250 or a 222 swift cal, and can I find an uppper that is compatible. I am in the dark on this subject, and would like to know. I could sure use some help on this yall. Any varmint hunters out here got suggestions/ideas/advice to share. Thanks in advance.