Not so sure what Bushmaster uses as the source of their forgings, or of their markings, though I believe the barrel should be marked: B MP or something like that.
As for the raised markings, those are forge marks, so they indicate that you've got a forged upper and detachable carry handle. The "keyhole" looking one is Cerro forge, IIRC, and the one on the carry handle is a Cardinal forge. Both are well known on AR components, my CMMG upper is a Cardinal, while my Colt upper wears a Cerro, so no worries about them being cast, and from what I know, they could very easily be Bushmasters, unless someone else knows that Bushmaster uses some other forged upper exclusively. I wouldn't imagine that to be true, though, I'd think they get the raw forgings from several sources, like most other AR companies.
Also, most companies, AFAIK, don't engrave or mark their flattop uppers, again, I'm not sure if Bushmaster does or does not, as I don't have any Bushie parts, nor have I really looked into them.
HTH, I'm sure someone will be along shortly to give you some more help,
~Augee