Thanks for your information，Hallo!
The Mauser "K98" rifles' butt plates were not blued (blackened), and should be bright metal.
"We" loosely call the Karabiner 98 kurz or K98k for short (auf English the Carbine Model 98 Short) or K98k for short.... a number of different names such as K98 or 98K.
It replaced the Karabiner 98b.
Trivia: The code name used on official documents when talking about production stats was "Adalbert." )