There is no "drop-in" carry handle for a flat top that will perform flawlessly. After you spend $130+ on the carry handle, reserve the same amount for a competent gunsmith to re-work it. These detachable handles are not perfected yet. They are kind of a blacksheep in Service Rifle.
I recommend buying a standard Armalite carry handle. It has a recoil lug that fits in the pic rail and really helps to get repeatable zeros when re-installing. Then have a competent AR smith put in the rear sight. Get stuff from Compass Lake or similar place. Don't re-use the standard hardware, get all new stuff made for the detachable handle. You want the highest quality parts.
The elevation and windage clicks need to be crisp and repeatable. A good sight insert with your desired aperture (0.40" is a good start). Have the smith do some work with the detent springs so the sight doesn't twist. I would also have the rear sight pinned so it tracks straight up and down.
Spending the money once on quality stuff, and not twice on crap.
I learned the hard way.
My carry handle has over $250 invested in it, but it works great. I put it on top of an Armalite 16" mid-length target upper. I have 28 MOA of elevation and shoots almost as good at 600 yds as my service rifle. My detachable handle is now a family heirloom and my wife hates me.
ETA:
You are just starting in the service rifle. Forward assist has a good point about bullet selections, but I suggest that you start with mag length Hornady 75s at 600yds. As you improve, you can start experimenting with the 75 AMAX, 80SMK, and 80 & 90 VLDs. H 75s are a little frustrating in the wind, but you have other things to worry about first. By the time you need the edge of the VLD bullets, you will be on your 2nd or 3rd barrel. Good luck.