Yes, it does look like the H&A. I'd thought about that one, but had rejected it fairly early on.
I was mulling this over in bed last night, sort of 3/4ths asleep, and had one of those "bolt out of the blue" moments...
My mind flashed "It's a Burgess!"
Then the rational part of my mind flashed "It's not a Burgess. That was a repeating rifle. Dumbass."
And then I rolled over and went to sleep.