What budget?
Chrome-lined barrel, yes, no?
Preference for handguards: Standard, free float, rails, no rails?
Oh, and do you want to buy a complete rifle or a kit? Or assemble from parts?
Right now a 16" Varmint kit from Model 1 Sales fits the bill. $510, plus an extra $100 for a lower receiver. Comes with a railed gas block and flattop. However, doesn't come with a chrome lined barrel, only options are stainless steel and chrome moly. Or you could just order the standard CAR; with free floaters its only $475, plus the lower.
If you are planning to just buy an entire rifle, sorry but I can't help you much. That's definitely not my department, though Bushmaster seems to be a good choice. Also Rock River Arms is a very good place to buy rifle parts, and they also sell whole rifles IIRC. RRA has a lifetime warranty as well
.
The most important things to decicing what you should buy are uses, price (if you are on a budget) and personal preference, in no particular order.
Welcome aboard.
-N3rd