From the brief description of the gun it sounds like the posts you've read apply to yours also. It's a Brazilian Model 1855. These were based on the Enfield, and made for the Brazilian army and navy. A 3-band version was made but not imported to the US. The first 1,500 arrived about the time of First Bull Run, bought by the State of New York. Total imported was about 6,000. The brass eagle shield was "probably" affixed by Hermann Boker before being imported. The ramrod sounds like a replacement. It should be .58 caliber, rifled with 4 grooves, although 3 grooves have been reported by others.