Given the confirmation you’re not trying to go ultralight, but rather simply wanting a rifle without excessive weight, then you’re really already there. The barrel is the single most influential piece of the AR puzzle. Barrels can move the needle by pounds, while everything else only moves inches.
A few more easy ounces can be bought by using an adjustable gas block, a semiauto carrier, and a carbine buffer, but again, these are only a couple of ounces. Personally, with a 6.8, I run full auto carriers and H2 buffers to slow down the reciprocating mass, and I ignore the slight increase on the scale.
The rest is pretty straight forward. Avoid a quad rail with a bunch of covers, and only use a rail long enough to cover your gas block. The Midwest G3 ultralight and Aero Atlas One mentioned here already are great handguards, but can limit your gas block options. I haven’t used a Nordic tube in a few years for a build, but they’re a nice and light full diameter tube. Use a normal carbine type stock, avoiding something overweight like the ACS, PRS, or UBR. The Aero Ultralight and Warne optic mounts are much lighter than the big and bulky Burris PEPR Mount. None of these choices are spending extra money to cut weight, but all of them are avoiding choices which add little bits of unnecessary fat.
Beyond all of that, the last thing is to avoid unnecessary bolt ons. No angled foregrip, no back-up iron sights, no 6” sunshade, no emergency fishing kit in the grip, no grip plugs or palm rests, no flashlights on a day rifle, maybe even skip the bipod and mount, etc. Adding anything is adding weight, so if it’s not application critical, or even application relevant, think hard about whether you want to carry its weight.