I've built a dozen or so, mostly 7.5", but a few 11" and never had issues with any of them. Most of them weren't technically a full build because I used Model 1 uppers but I did fully build a couple with various parts. They are a lot of fun and IMO very little recoil, but I always used a full length buffer and tube due to reliability issues with the short ones.
This is the only pic I had handy of any of them. This one was for a relative but had a Stag lower, Model 1 7.5" chrome lined upper, RRA trigger, hogue grip, some cheap red dot he had, and a cheap gun show flash light that doubled as a front grip.