Properly applied powder coating does not involve dipping anything. Think of hanging your rifle on a wire. This wire is connected to an electrical source with a positive charge. Then, a paint sprayer is used to spray the powder onto the item being coated. This sprayer is connected to the negative terminal of the electrical source. This causes a static attraction for the powder to "stick" to the item being coated. Then, the coated object is baked. Upon baking, the powder melts and bonds with the coated item.
Powder coating tends to be shiny due to how it is cured/baked. However, it is an extremely tough finish that is much stronger than other applied finishes. This is why it is so popular for motorcycle frames and wheels. The problem with the DPMS is that the parts are conveyor fed through a spray booth. The powder tends to fogand get into everywhere. If you were to have something custom coated, it would be done on an individual basis with a hand sprayer and areas that you don't want coated would be masked off. This will prevent overspray and potential clearance problems.
It is up to you, but I would not be afraid to have one powder coated.