I know that particular rifle, might have had a set-up for sidemount, and I see too the boltscroud, might be un-original...but my thinking is this..based on earlier rare encounted iterms, that I have rejected, because one screw didn`t look right. I am gonna keep this rifle for many years, and I know a good gunmaker that can fix it all so nobody can see anything...exept a fine rifle.
Many years ago I passed a Colt Bigframed pumprifle in 50-95. The finish was not original as decribed by the owner, but I was sooo focussed, that it had to be 1000% original. I could have that thing for $2000( 9 years ago). I have passed a Martially maked Colt SAA, because someone have replaced the onepiece walnut grip with stag.
I guess I become more lenient over the years...and that rigbymauser takedown in .303 is a rare duck in the entire ocean + I really have a soft spot for rimmed cartridges, and here is one of the kind. I don`t think that more than a handfull original takedowns, .303 was ever made.

Think of this guys: Imagine this .303 rigbymauser being 100 % original, for sale at puglish Emporium?..$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$