Honestly I didn’t build this one haha, this is one I bought from a CGN’er while I wait for my email to show up! I changed a few things here and there but nothing major. My hand guard I bough for another build wouldn’t over the gas block so I stayed with the original, otherwise it would’ve shaved off another few ounces. For the BCG I assume the original owner knew about the lightweight ones not working well with ejection port covers as he had another one as well. But I can’t say for sure. Once I get my two other MS’s built I’ll post them as well along with compatibility issues if I have any.