I love this subject as I'm a student of photography and doubleguns.
I think there are multiple approaches to the subject.
The method above produces a technical image of the gun.
My makeshift approach to technical pix on a trip where my equipment was limited was to use a blanket held a few feet behind the gun and an open apeture to blur the background. The handheld off camera single flash was held at a glancing angle to the gun surface to accentuate the engraving.
Another approach is the 'diorama' where the subject is in what appears to be its natural setting but is usually composed.
Other articles are included and texture is often an interesting addition. In this picture the flash was bounced off of a white ceiling which causes a very 'soft' lighting effect that appears more natural. This effect is similar to the 'overcast day' effect mentioned often by still-life subject photographers.
In the picture above, I think I used this method with this camera. It's been awhile and I can't recall for sure, but this method works well with a white ceiling with a 'on-camera' flash that is TTL metered like the Nikon SLRs. It's kind of a billiards game. But with digital photography, you can test the effects and compensate quickly.