Well, first off I have to say that this overhang you have doesn't sound at all right. Worse still is that I see no way to assemble an M41 so as to cause this(or at least, not my 1970ish M41). Take it back apart and see if there is maybe some grit or debris in the works somewhere. If all else fails you can always call S&W and ask to speck to the service dept, or take it to a good gunsmith.
I don't know what the problem might be, does the breech face appear to be completely flush to the slide face? Look on the left side and there should be no visible gap between the two surfaces. If there is a gap then the slide is being somehow prevented from closing completely, you'll have to figure out why.
I hope some of this was helpful, good luck on solving the problem.
Don in Ohio