I want to put an M lock style upper on my rifle; I'm not wild about the big front post sight, and will use an optic instead that's for closer quarters than the Eotech that's on it now. I'm pretty new to AR stuff; just wanting a reasonably priced M lock upper that I can match a decent optic with. What brands or styles should I be looking at?

__________________
MARK

The front sight and a cheek weld can save your bacon up close and personal if your optic dies.

You don't need to change the entire upper. Pre M lock I went with a Mag-Pul fore end, they may/may not have invented the M lock.