This is...odd.  I'd like to see that mesh, try to understand what happened to it.

The major problems I've had with non-bending objects (like a gun) are reversed surface normals, the "marshmellow" effect mostly addressed by Poser 6 (with the ability to set creasing angle on a per-object basis), and a variation of the above present in Firefly renders that I call the "bagpipe" effect; where a long cylinder will "inflate" like the bag on an upright vacuum cleaner.

All of these have solutions, though some are more onerous than others.