The thing I found really odd was the size of this cap. It is hard to do justice to this on the pictures as with all things you need to have them to hand really.
The cap is much bigger than a field cap in all its dimensions and has an almost beret shape.
The field cap is only approx 8cm high and the cap band is 2.7cm approx. The shape of the cap is also more squarer and box like.
This cap has a cap band of 3.5cm and is 8.8cm high. The cockades also don't match the stamps.....then I had a moment and realised what it was.
It's a 1919 field cap for the reichswehr with the cloth peak missing take off the peak and its a dead ringer for an m17 which it was of course based on. The cockades I reckon have been added later (although very well done ) as the other stamp is for JR7 a prussian unit.
The other stamps are well faded but underneath the bja stamp is HBAB 192? acceptance stamp for berlin clothing depot.
The RJA stamp is for the clothing repair unit of the IV army korps so my theory is the cap was damaged and they took the peak off and put into storage. It was maybe issued again to JR7 as m17 caps were used by both regular and training units in the field.
Mystery solved and a rare cap to find even with the peak missing.
Here are some comparison pics...................
Thanks for looking