Abstract: A black powder firearm (10) is easily disassembled and has interchangeable barrels (12) . Barrels (12) attach to a receiver (24) at a bore (86) in the receiver (24). A lug (50) attaches to the barrel (12) and bolts to the receiver (24) through a hollow lug bolt (46). A bore (98) in the lug bolt (46) holds a ramrod (20) and allows the ramrod (20) to extend into the receiver (24). A breech plug (54) screws into a breech end (16) of the barrel (12). A nipple (58) of the breech plug (54) extends through a hole (88) to engage a hammer (30). A base section (56) of the breech plug (54) abuts a steel portion of the receiver (24). A trigger mechanism (28) has a linear, coil compression hammer spring (102) that is pivotally anchored to a trigger housing (62). This anchor point is displaced from a pivot point for the hammer (30). An anti-blow-back lever (124) engages the hammer (30) when the hammer is in its fired position and a trigger (32) is pulled.