Personally I think your concentrating on the wrong area here. I mean it is conceivable that when you join the space marines or whatever, you'd get a new shotgun - hell you might even be expected to pay for it yourself!.
The other texture had too many scratches and not enough scuff, this one has too much scuff and not enough scratches
. I would reduce the scuff a lot, and introduce some scratches too, maybe even flake the metal coating a bit where the scratches are deep. If you consider the areas that would get scratched and only do those, then you'll have a much more subtle effect and people won't see it as a wannabe texture, it'll be a thought out texture - professionals are just as likely to overdo these things. I would make the gun shiny and new, then tarnish it - wear down the areas that would get scuffed as the gun is put away, mostly the end of the barrel, some of the length of the barrel (not too much), the thinner parts at the top would take a lot of punishment, as would the area around the hammer.
This is assuming that you want to make the weapon look worn - if you want it to look more like a warhammer model, then the wear on the gun metal needs to be quite smooth, lots of shading and less of a worn paint look, more like a worn coating, which would wear down much more smoothly. A subtle edge highlight would work well I think, with some nice shading.
