If it's high and tight, very comfortable for hiking and dodging in and around trees and swamps, able to get on target instantly, the shell deflector bumps me right at the bottom of my sternum. Have not figured out a path to engineer my way out of this. Makes me not want to carry it. Grinding it off seems a really poor solution.
Do I have to wear amour in the summer?! I'm seriously considering a plate-carrier style vest, just can't find one that could replace my backpack. I'm kinda needy in the woods, pack out a kitchen sink kinda needy. Carriers look quite nice, and would keep my gear out the water when I wade or slip, don't seem to carry much.
Maybe get a simple one and attach bags? Maybe attach more crap to my Fighting Load Carrier (FLC)? OK, you talked me into it. Thanks rubber ducks!
I'm not a lefty so unfortunately I don't have any good tips for running your sling. But if it were my rifle the first thing I would try is sticking a big wad of Sugru over the area between the deflector and the forward assist, and mold it so it flattens the area out, or rounds it out, so it doesn't poke as much.
Beyond that, you can get upper receivers that don't have a forward assist or brass deflector at all. It's more common for pistol-caliber uppers, but they do make them for 5.56 as well. Probably just be conscious of the size of the ejection port so you don't accidentally buy an AR-9 or AR-22 upper.
Also, you can get just full-on left-handed upper receivers as well. They're basically just a mirror opposite of a regular one. These tend to be on the expensive side though because they also need a left-handed bolt and bolt carrier to work.
If I remember right the brass deflector is there because of lefty and offhanded shooting situations. Without it brass can fly back and hit your face
You can tune your gas system to mitigate that if you need to. There are some variables involved, but it's usually not too hard to get your brass ejecting around a 3 o'clock angle.