Welcome to the forum. I am not trying to talk down to you with the rest of my post. You did not indicate your level of firearm knowledge, so I will keep it pretty basic for now.
Have you shot the rifle yet? If not, I would not worry much about it being tight. Things will get looser as it breaks in some. I would recommend soaking the BCG in some Mobil-1 overnight before you head to the shoot it. Wipe off the bolt face and let a little of the excess drip off. Then put it in the rifle with a lot of lube still on it. As long as it appears safe, shoot your rifle before doing anything other than lube.
Also, you might look at some of the other threads in the PSA section to see what kind of problems you might experience when shooting. PSA can make a 308AR that functions normal most of the time. However, there are some issues that regularly present themselves. It would be wise to be aware of them as you shoot.