Luger 41/42

I found a Luger today (at a gun shop I dont really trust) that had a Luger for sale with a 1941 marked barrel with a 1942 receiver. It was a Byf with all matching numbers including two magazines. Looks as tho it had been refinished ----finsih almost black with black grips.... Unfortunately I dont remember the serial numbers. Since I am new at collecting Lugers what should I look out for. Thanks David