Deer vary so much in weight and antler size by region across the country that it's pretty much impossible to set a single standard for what constitutes "big".

For instance, I've killed one 160 lb. dress weight buck here in western MT, so it meets your basic standard. But, it was only 3 1/2 years old and net scored 109, probably not what you had in mind as a "big" buck. Going back over the family's kills over the past few years, we have taken 7 3 1/2 year old bucks (with rifle). The average score is 110 net, range from 102 to 121. Body weights (estimated in most cases) would range from 140-160 lbs. dressed, plus one eastern MT buck I took that dressed approx. 185 (still 3 1/2 years old).

I believe all 7 were taken between 10 and 30 Nov.