Though your Columbian Mauser is not a suitable donor for your "Tiger" rifle the receiver is still suitable for a rifle build as a "truck" gun.

As is the receiver will be stuck in a stock if you where to glass bed the rifle as the below wood pitting will lock it in place.

The receiver can be sandblasted and the pits then filled with an epoxy, like J. B. Weld. The sandblasting will give the metal "bite" to hold the epoxy. The epoxy is smoothed to the receiver contours. The receiver can the be spray finished with Gun-Kote, a baked on finish. The sandblasting of the recieve is also benefit in preparing the receiver for spray finishing.

You will be left with a tool grade receiver/rifle when finished but by no means and exhibition grade.

Vlad