The smoothing on the silencer was meant that way - it's on the sides you don't really see, and giving those front faces the same smooth group would negatively affect the quality of the smoothing of the parts you do see, from the V model perspective (look at the awkward shading on the rear section of the silencer from all that part being the same smooth group - though that bit's right in your face, so I thought I'd make that bit seamless).
That's how it was done back then, heh. Tricounts had to be kept as low as possible, so it seemed a bit wasteful to add geometry to make the smoothing... smooth :P The model's around 15 years old, at this point, so... yeah :D
Where did you find the model? I lost it years ago when my HDD died.