Doug it's hard to tell too much without photos, but sounds like a postwar gun to me.
If it was made before or during WW2, it should have the letters "DRP", for Deutsche Reichs Patent, stamped somewhere on the receiver. "Made in Germany" is seen on postwar guns, it was a few years before they added the "West" to this.
If you will measure the overall length and barrel length, you can compare to the descriptions in Hiller's book (or post them here of course). The stamped cocking link also sounds like a postwar detail.
This photo shows three model 27's which should be similar to the 25. The gun on the left is pre-war, has DRP on the left rear receiver, solid cocking link, and slider-type rear sight. The gun in the middle is from the mid-1950's--note the slightly different breech block shape and stamped cocking link, but the wedge detent and rear sight are nearly identical to the older gun. The rifle on the right is from 1981, note improved rear sight, ball-bearing detent, and bigger rear sight.
