I’ve never seen a two piece plate joined like that one. I have seen two piece plates that were riveted, and then forge brazed. And, to be honest can’t really understand the reason for the two pieces being made separately in the first place. I can only assume the builders lacked the tools to produce the narrowed contoured area where the buttplate, and return, join. I own a beautifully made SMR buttplate made in one piece, and then bent, and brazed together. It just seems like it would be harder to keep two separate pieces straight while brazing.
Hungry Horse