After every trip to the rifle range or your hunting grounds, you should thoroughly dry your firearm and wipe down the bolt as well as the exterior metal portions with a lightly oiled rag. As far as cleaning the bore, the inside of the barrel, of your rifle, there are many different opinions on how often it should be done.
However, the basic answer is that you should clean your firearm before the bore becomes so fouled that it has an adverse affect on accuracy. Dirty barrels are probably the number one reason that otherwise good shooting rifles turn bad. Depending on your gun, that could happen every ten shots or every hundred shots. If you want to be on the safe side, clean your rifle after every trip to the range, assuming that you shoot a couple dozen rounds. Some shooters claim that over cleaning/brushing can harm the bore of a rifle, though no part of the cleaning procedure exerts as much force on the barrel as a bullet that’s traveling close to 3,000 feet per second. It is not necessary to clean your firearm after a hunting trip unless you did a lot of shooting or you got debris such as sand or mud (or worse, saltwater) down into the barrel.
Getting a barrel truly clean requires a few tools and products that are widely available, plus a lot of work.
Here’s the Procedure