The Bravo Co BCG is a quality piece, which is why people like them. The bolt already comes with the o-ring for the extractor (and an extra one in the packaging). It's also magnafluxed and high pressure tested. Key is staked properly.
Plug and play and don't worry. Also, when I got mine, it was clearly test fired to ensure it worked, as there were brass marks on the bolt face.
"...and an old German guy said there was a bit of an unsaid joke about the Nazi salute; apparently when they clicked their heels and raised their arm up in the air in a Nazi salute, they were saying, "we're in this much s___."