I have looked and can't find info on this, does anyone know, I have several receivers and would like to separate them. Wallacem
SB2 marked on the barrel means nothing, many of the early(2008) SB1 357 and 44mag rifles have barrels that are marked SB2, barrels are made in runs of 100-500 long before they're fitted to a frame. Frames aren't marked SB1 or SB2, the only way to tell them apart is to know the difference in how they're made, the biggest difference in appearance is the tang of the SB2 is skeletonized, the SB1 is solid. SB1 are cast iron, SB2 are heat treated investment cast alloy steel, there are pics showing the other differences at GBO. Madison CS can tell you what acc barrels can be fitted to the frame by the serial number also, toll free (866)776-9292.Jake said:Mine says SB2 on the side of it.