Merrill Carbine, .54 cal. percussion carbine.  Serial #5571.  Antique. Civil War. Good condition.  22 1/8” barrel has rough, pitted bore with no remaining outside finish and some surface corrosion.  Lock plate and hammer have fading finish with crisp markings and surface corrosion.  Stock has good original finish with lots of handling marks and large letters; “SH” carved into left side.  Nice brass patch box and trigger guard.  Saddle ring intact.  Unique “monkey-tail” action works perfectly.  Nice piece of Civil War history!  Antique, can ship to your door.