OK, it's not a revolver, but then we've had some other weapons mentioned in this thread already.
DeNiro's folding stock Sig551 in Ronin:
http://www.imfdb.org/wiki/File:Ronin_Sig551A.jpg
DeNiro's folding stock Sig551 in Ronin:
http://www.imfdb.org/wiki/File:Ronin_Sig551A.jpg