The reason it does not have Waffenamt stamps is that it was not produced in Nazi Germany. In fact it was not produced in Germany at all. Your rifle is not a K98k. Note that it has no steel thimble in the stock, the buttplate is rounded at the top, the handguard and rear sight are not correct for a K98k, and it has no bolt handle cutout in the stock. Since it was not produced under the Nazi code system, it does not have a factory code or date stamp.
It looks like a Belgian short rifle, or possibly a Vz24. Without having it in hand, it is hard for me to tell exactly what you have (I am sure one of the forum experts will come along soon and give us his opinion), but it is not a K98k.
Just as an aside, the Mauser 98 in its many variations was at one time the most common and desired military rifle in the world. Many, many millions of M98 rifles were produced in Belgium (FN), Austria (Steyr), Czechoslovakia (CZ), Poland (Prague arsenal), Yugoslavia (several arsenals), Spain (La Coruna), Mexico, Brazil (Ibatuba), and yes, even in Germany by numerous makers.