Good light is probably the biggest thing I’ve come to realize is absolutely necessary. I prefer the Streamlight HPL because it definitely has a “reach out and touch you” sort of beam. If you’re using an optic, one with adjustable brightness(Eotech or Aimpoint basically, nod to the Aimpoint for being able to leave it running all shift) is a must because of the constant varying ambient light. Trijicon optics seem to have a HUGE issue with the tritium being washed out by lights that are bright enough for good outdoor use.
I’ve never messed around with the tritium night sights for Ar’s as I use optics. But, basically. A good light is mandatory.
I run a 200 lumen, 2 cell Surefire scout light on my issued work gun and a 1 cell 200 lumen (newer technology) on my personal work gun. Both are in offset mounts with clickie tailcaps. Aimpoint on both. Hudreds of operations including entrys, field search, and regular patrol and I have never needed a brighter light though I have been blinded multiple times with my surefire x300 ultra 500 lumen pistol light. It’s too bright. YMMV.
If the OP works for an SO he could end up in both environments (rural/urban) easily.
OP, we issue Shrubmaster M4’s with the Aimpoint PRO. <---- Great optic for the money. Can be had for < $400. The optic is designed to be left on and give 3 years battery life. We swap the batteries once a year during quals.
I use a VTAC 2 point padded adjustable sling. Botach makes a great copy for $20.
I do a lot of consulting with various depts as part of SIONICS and I get asked about this stuff in my classes all the time. I have found that the Surefire X300 series lights mounted at the top of the rail (12 o’clock ) is almost the ideal set up. A good sling is a must and I highly recommend a good red dot. Part of the missing equation here is that you haven’t told us anything about how your weapon is configured (pics would be nice). If you have a carbine with an FSB that changes the equation and will necessitate different options. Another good option for mounting a light with FSB is the Mossie Tactics Midnight Mount.