In New England most of the states have a 6mm minimum for use on deer, so I don't see the .223 taking over around here at least.
I beg to differ....
How so?
Last count I knew of the .22 CF or smaller as a few state "Any Centerfire" was legal for deer in 38 States and a few Providences in Canada. So I think that is what fatjack34 "begs to differ" on.
No problem, but he did not provide any specifics. Possibly Vermont, but not NH, CT, or ME. For big game that is.