the 556/.223 is NOT a very good deer caliber, and its NOT even legal on many states, si, IMO< skip that caliber for a deer rifle here!
next, after deer season, start going to gun shops, be surprised how many folks SELL a gun after deer season to buy X mas gifts
I had a gun shop and would BUY a LOT of used like new rifles, many times SOLD them the gun before deer season and then they sell afterwards back to me?? and as such, you can many times find very good deals on lightly used deer rifles with nice scopes and all set up!
very very few people shoot a rifle enough to even come close to wearing the bore out, just costs too much $$ for most folks to do so!
so, used rifles can be great buys