Very nice photos. IMG 4098 is a very rare piece. This is the German 10,5cm lFH Krupp 1916, which is nothing like the standard 10,5cm lFH 1916. Notice it has no axel tree seats and has bands on the barrel See the two identification pages on the 10,5cm lFH Kp 16 and 10,5cm lFH 16: