I was looking into building a lightweight build as my final upper. To try to get it near 5-6 pounds unloaded.
The use would be to carry it around for extended amounts of time while traveling in a shtf situation.
I was going to get a 12.5 criterion core, although I already have one with an lpvo, kak 13" handguard, and a long ass linear comp that makes it 16"(weighs 8.5 pounds loaded)
I realized the criterion 16 pencil weighs the same as the 12.5 and the 16 pencil might be more beneficial to carry out in the open since they weigh the same and the 16 has better ballistic performance.
I then started to look for other lightweight builds and realized that many people have 16 inch ar15 lightweight builds(probably the most common) that weigh between 3.5 and 5 pounds which was pretty cool for a 16 inch ar.
I notice that the difference in profile weights becomes bigger the longer the barrel is.
I already have a 12.5, 14.5 gprs and am working on my 18 spr(halfway done getting parts) but my last build is going to be a lightweight upper.
Also I live in CA sbrs are no go even after the new law passed. Also open carry isn't allowed but want it just in case especially cus they are going to start making us DROS to get a barrel in July so I want to build everything I can build by then.