When mounting a rifle on the wall, you can get as creative or as simple as you wish. Determining how fancy you wish to get depends mainly on why you want to mount your rifle in the first place. For example, is it an antique rifle that you're hanging strictly for decoration in your home, or is it your hunting rifle that you wish to keep accessible on the wall of your Highland hunting lodge? Before mounting your rifle on the wall, make sure it is unloaded.
Build or buy two wall mounts or a one-piece wall mount assembly. The mounts should have a rounded groove on the inside to support your rifle. If you're trying to do this on the cheap, a couple of long nails will sufficiently do the job.
Find a place on your wall high enough to keep your rifle out of the wrong hands. Mark off the height.
Secure the rear mount to the wall, preferably by screwing it in. If you're using a one-piece assembly, simply make sure it's level and screw it to the wall. If you're using a nail as your mount, drive it in with at least 7.5 cm (3 inches) protruding and at an upward angle (about 15 to 20 degrees). Wrap the nail in protective tape -- such as electrical or duct tape -- to prevent the nail from scratching your rifle. Do the same when securing the front of your rifle.
Place the back end of your rifle on the mount and, while holding up your rifle, position the front mount on the wall so that the rifle is level. Mark that position and take down your rifle.
Affix the front mount to the wall and hang up your rifle.