Burnside civil war carbine, 3rd type, cal 54 Percussion

Burnside civil war carbine, 3rd type, cal 54 Percussion   Flayderman P 618, item 9B 044

Serialnumber 3854, , standard 21 inch barrel, bore is dirty, needs some cleaning, markings are light but there, stock is fine, normal amount of smalldigns, thin buttplate, correct for this model, plus the covered screw on underside of barrel, not to be seen on the 4th and 5th model. 
Approx 1500 made of this model. Works fine,