So does this apply to 7.62 AR's as well? Is an AR-10 lower for something larger than .308?
If you are still interested in a .308 AR, see Palmetto State Armory. I built one with their parts. It turned out nice. Shoots well. I bought a stripped lower from them and discovered that building a lower is easy. I haven't had the nerve to build an upper yet.
I agree. The only hard part was winding that #$*@ spring for the ejection port cover and holding it in place during assembly. THe gas tube wa a bit of a challenge, but with a jig from Brownell's it went well. I have only done one complete, but if you have the proper tools, it isn't particularly difficult. I recommend Walt Kuleck's book on AR-15 assembly.TBH, I think it is easier to build an upper then a lower. I have done a few. They are not that hard to build.