You are entirely correct they are KAR98a blew up the picture and compared with Mauser Military Rifles Of The World.I'm not seeing any Gew 98s, mostly Kar98as, and a couple of Gew 91s. Clearly an artillery unit, possibly some kind of Reserve unit judging by the age of some of the men.
Please could explain a bit more for someone who doesn't have your knowledge.Difficult to tell with the Uberzugs but it looks like they are wearing Artillery helmets. I think the 15th Fuss-Artillerie Regiment
Prussian Artillery helmets have a ball on top instead of a spike, so that identifies it as an Artillery unit. There were 2 types of Artillery in the Prussian Army. Field Artillery and Foot Artillery. Referring to the Kaiser's Bunker page on Foot Artillery (https://www.kaisersbunker.com/gtp/New/af0.htm) you can see that the 15th Regiment had white shoulder straps with a 15 (like the guys that are wearing dunkelblau in the photo). The 15th Field Artillery regiment on the other hand would have had green shoulder straps with a red bomb and 15 (https://www.kaisersbunker.com/gtp/New/fa0.htm). They also had different type of cuff. The uniform descriptions on the Kaisers Bunker are excellent and he has them for all the different type units. https://www.kaisersbunker.com/gtp/Please could explain a bit more for someone who doesn't have your knowledge.
Thank you
Thank you for taking the time to explain I will read furtherPrussian Artillery helmets have a ball on top instead of a spike, so that identifies it as an Artillery unit. There were 2 types of Artillery in the Prussian Army. Field Artillery and Foot Artillery. Referring to the Kaiser's Bunker page on Foot Artillery (https://www.kaisersbunker.com/gtp/New/af0.htm) you can see that the 15th Regiment had white shoulder straps with a 15 (like the guys that are wearing dunkelblau in the photo). The 15th Field Artillery regiment on the other hand would have had green shoulder straps with a red bomb and 15 (https://www.kaisersbunker.com/gtp/New/fa0.htm). They also had different type of cuff. The uniform descriptions on the Kaisers Bunker are excellent and he has them for all the different type units. https://www.kaisersbunker.com/gtp/