I would like to branch out on my next AR15 project. 1. I want to build the Upper myself, instead of buying a complete upper assembly. 2. I'd like to go with a 20" barrel. a. I want to try something different. b. I want to work on shooting longer ranges. It will probably take all year to get the parts in "dribs and drabs"; if and when stuff become available. But I want to plan ahead. I've become a real PSA-bigot. After my first build worked so well, I want to stick with them. On their description for their barrels, they say : Most of the things I've read so far suggest that headspace will likely be ok. Does that sound right to the experts on here, like Quentin and others? I got such good advice before, I want to be sure to make use of it.