machine gun fired .308 brass

I don't see why not.
~4 weeks ago bought 1K 308 mil brass off a guy on AR15 for $180. All LC head stamped
I've processed 500, loaded 100. Except for the crimp, looks, weighs measures and feels like all my other brass.
 
Just plan on using a Small Based die and I'd even anneal it before loading the first time. Once fire-formed it's great brass. More durable than a lot of commercial brass but not as uniform as those like Lapua. Weight sorting and close attention to prep can make it perform about as well as any other case.
 
Its all I use. I have used a SB sizer but have found over the years its not necessary. I guess since the military switched to M240's the brass isn't as beat up and over sized. Back 15-20 years ago when it was being fired through M60s it was necessary to use a SB sizer.