younghunter12,
An inline rifle has the nipple/flash hole that enters the bore (usually through a removable breech plug) in the center of the breech end of the barrel 'inline' with the bore. These can be of many different types: Plunger actions that strike a #11, musket cap or 209 primer. Break open, drop block, swing block designs like a single shot shotgun/rifle that use a 209 primer or small rifle primers loaded into small cartridge cases such as the .25 ACP for ignition. Bolt actions are another popular design that use a 209 primer or the rifle primers in a .25 ACP case for ignition. These are still considered percussion ignitions for the most part, but unlike the side hammer percussion and flintlock rifles that have a flash hole that enters the barrel usually at a 90 degree angle (thus 'not inline') to the bore of the barrel.
The inline rifles usually have a much faster twist rifling (1-20 to 1-28 ) than most 'traditional' rifles (1-48 to 1-70) and shoot either long heavy full bore conical bullets or the more popular light saboted pistol bullets.
Bottom line is they are all muzzleloaders and load from the muzzle, but most of the inlines use Black Powder Substitutes (Pyrodex, Triple Se7en, Pinnacle, American Pioneer, Black Mag'3) while most of the Traditional Guys prefer good ole Black Powder (Goex, Elephant, Swiss, etc.) in there sidelocks and flintlocks.
That is NOT everything you need to know, but should at least give you a basic idea.
[EDIT] I started to answer you and had to go do something else, came back and finished but kieth snuck in there in the meantime. :grin:
