Interesting that it has a 12 barrel stamping above the choke stamping... I'm no 97 expert, but I've owned at least a dozen and have 5 now and not a single one has ever had a 12 stamping there..
From what I gathered online it could be a hard rubber buttplate or a metal one. It could possibly be a convex metal one.This may be of interest:
Original buttplate could look like this:
View attachment 185764
That's what I was originally going by. I misread the s/n before I picked it up.I have found this reference to be handy.
According to it appears to be manufactured in 1904, or perhaps depending on how the info is interpreted 1905.