As was stated, guns are notoriously hard to photograph well. The photos you provided are not that bad, but busy backgrounds like a woodpile, or a Persian rug, or just a busy landscape, are terrible. Lighting is difficult on firearms because of all the shadows, and reflective surfaces. A old style clamp on hog light with a piece of cheese cloth stretched over the face, held in place with a big rubber band, reduces the glare, and defuse the light. A gray, or tan neutral background, without a reflective surface helps. You must always be aware of the shadows as well.
A guy I know that photographed our local museum collection for insurance purposes, used an old one piece fiberglass shower stall, lined with photo gray material. He made a fixture that fit the drain hole with several different sizes of brass rods to accommodate different bore sizes. It worked very well.
Hungry Horse