Boom! I can only assume this is the Assault Carbine we've heard mentioned a number of times by various 343i folks. Looks to be a mix of UNSC and Forerunner in aesthetics, with the stark angles of Forerunner architecture with the ridges and small detail seen in many UNSC weapons. Sweet!
David Ellis just posted this on NeoGaf:
Forerunner Pro-Pipe then? Niiiiice!
Thanks to WJD on NeoGaf for posting the image, my copy hasn't arrived yet.
- Cowboy Out.