I have a 120MM primer assembly for an unknown US or German tank round that utilizes a combustible/consumable case system. Due to the length of the tube extension, I am guessing it goes to a HEAT round? Anyhow, I was surprised how many parts its was made of so I took a few pics. :-) I am not 100% sure how it works but know these rounds are electrically ignited.
A pic showing similar primer assemblies in other 120MM tank rounds
Completly Assembled Primer
Base of AFT Cap Of M829A1 Showing Primer Back