Hello, welcome to the forum.
I am away from my home right now (at work) so can't look and see if 7057 is within the Bannerman numbers (it is within the accepted "range" of Test Lugers.
Dwights' commericial database shows that it has a mismatched toggle?
That makes a difference in value; as does the missing extractor and hole in the frame.
I would say depending on how many other parts mismatch, at $1600-$2400; maybe more, maybe less.
I don't have a Biseley and just 2nd and 3rd gen Colt revolvers, but interested in it.
weimar_lugers@verizon.net
Ed