You mentioned a "standard weight BCG". By "standard", do you mean a commercial, or M-16 profile BCG?

Two most important parts are the barrel and BCG.

What's you budget for each?

As for your 200 yard limit, a properly set up 16" carbine that's good for 200 will be good to 500.

You didn't use logic or reason to get into this opinion, I cannot use logic or reason to get you out of it.

You cannot over estimate the unimportance of nearly everything. John Maxwell