I believe they were filed in for the most part given the ones I have seen there are a couple examples in my photo collection that are just such.. There maybe some out there that could be formed that have significant fluting which means they were made from thick stock. The use of thinner brass that was formed to give the initial shape before the final clean up filing was done is also possible. I use the later technique for the forming of wedding bands and entry pipe details for my rifles.
