NSKK Experts; know this marking?

[Nashorn1944]

On the stock of a training rifle (.22) is a NSKK eagle stamped into the wood, on the sides of the eagle are the letters 'M' on the left and 'U' (umlauts) on the right. Does this stand for 'Motor Ubung' (Motor Training)? Perhaps it is a Motorstandarte? Any help would be great! -MB

[Nashorn1944]

I figured it out...

...those interested in the NSKK, 'M U' on either side of an NSKK eagle stands for "Motorsportsschule Ubungsanzug," these were training rifles assigned to the NSKK Schools. -MB