Re: Remington .41 o/u Derringer
Using Flayderman's terminology, that is the Type II or Model No. 3, some 80,000 made 1888-1911.
The screws are definitely not factory and further aren't where those guns usually crack, which is in the little frame loop itself, further forward. From examining some of those guns, I have come to believe they don't crack from firing, but from the barrel block being opened fast, breaking the loop from its momentum.
I believe that gun was cracked at the point where the screws are, was repaired using the screws, then polished and (re?) plated. That model, in excellent condiiton can bring well over $4000; even poor condition ones (that are not broken) can bring $1500. The problem is that I am not sure how much impact the repair (if that is what it is) would have on the value, let alone the (as I believe) replating.