Yes, all USCIS offices have FOIA units in them that respond to FOIA requests. The only concern I would have would be that the FOIA unit would have to request your physical file from wherever it is currently processing (assuming you have some application/petition pending on your behalf) to make the copies and get them out to you. My guess would be that one of two things would happen--1) the FOIA unit would request the file but not get it (and not get you the copies) until your pending application is resolved or 2) the FOIA unit may get priority and get the file and pull it out of whatever queue it's in. i'm a caseworker in a congressional office, and I have definitely seen the first scenario happen, but i don't know what the odds are of the second. in any event, yes, you can FOIA your a-file. sorry for a long answer to a short question.
more information on CIS FOIA requests here:
http://uscis.gov/graphics/aboutus/foia/request.htm