When I was in Iraq in 08' I was issued a SIG 226. SIG magazines can work in the Beretta M9/92 if you hold them in (or vice versa). It won't lock up however, just something to know on the battlefield when the soldiers carry the M9 and you a SIG.
I did modifiy one Beretta mag years ago for my CZ75 preB. Had to cut a new mag release notch in the mag. Worked somewhat but give up on the conversion as I deployed again. I had 11 mags for my CZ and over 30 Beretta mags without a pistol.
CD