Player's Strange Background Options

[DnDer]

One of the players at our table, a first time runner (in fact, I think I'm the only one who's not) came to me with a strange background request, and my Sixth World knowledge is failing me.

He's a heavily-chromed, heavy weapons kind of character. Machines guns and cannons, etc. He has zero actual backstory - something that comes from not knowing the setting, I think - and said he wants to be a vat-grown person. Someone bred to be a living weapon. He's managed to pick up an Forger of False Identities for one of his contacts, so it wouldn't be hard to write in that she was one of the first people he stumbled across on his escape and set him up with his first identity. But what about before that?

I'm familiar, to an extent, with SR3, and the timeline. But I can't remember or think of any corp or organization who'd grow soldiers out of vats. We're starting up in Seattle, but I suppose it doesn't make a difference as he could have escaped whatever facility in a number of ways. Who would do something like that, so I could give him a brief rundown of what his backstory should entail?