Reichsrevolver Unit Mark

[Pistol]

I picked up an AWM reichsrevolver holster with the mark:
4 Fd A.R. for 4th Feld-Artillerie- Regiment.

I know AWM luger holsters typically went to Bavarian units. Is this also true for reichsrevolver holsters?

I think it belonged to two possible regiments:

(1) 4th (Magdeburg) Field Artillery "Prince Regent Luitpold of Bavaria" of the IV Army Corps garrisoned at Magdeburg.

(2) 4th Royal Bavarian Field Artillery "King" of the 1st Royal Bavarian Corps garrisoned at Augsburg.

What do the experts think?