When it comes to building an AR-15 weight is a factor I always consider. Unless you’re building a long range rifle that will only be shot off of a bench I believe lighter is always better.
A good way to shave off ounces from your AR build is to use a lightweight lower receiver and lightweight bolt carrier group, or if your budget allows it carbon fiber or titanium parts. If you’re not building a race gun or you don’t have a large enough budget you can save weight by simply using only iron sights and not adding every tactical do dad all the operators use, that’s hard to do I know. If you are shopping for parts for your next AR build or you plan to update your existing AR-15 check out this extremely thorough AR-15 Parts Weights Database.
MrGunsnGear shared the database on his Facebook page that one of his viewers complied. The data base has the weights (in ounces) for hundreds of various AR-15 parts from many companies. From upper receivers and parts, lower receiver parts, bolt carrier groups and parts, barrels, rails, muzzle brakes, buffers, stocks, optics and mounts, weapons lights, magazines and other accessories. A lot of time was spent on this database, a big thanks to those who put this together!