Interesting photos and links. It sometimes occurs that authoritative links do not agree with our memories and this is such an example. I was captain of an American Legion marching band bugle corps in MA in the mid 1960's. One of my roles was to signal with a raised left hand to the buglers behind me the next song to be played (the right hand tucked in the bugle to my side). Typically, these were about five WW1 popular tunes such as "Over There". If there was a reviewers' or judges stand, we would play the song we were performing best for them (and I would signal for it and lead). Although we had to polish our bugles before every weekend parade, I can't remember any maker's marks on mine. I do remember that it was shorter than the Conn pictured here and the scent of Brasso is one I can never forget. I was always under the impression that our bugles were mil surplus, probably WW2 vintage. They were not adorned like the example in the OP's image, though the rings were present.