Used by the German Army on an M-109 155mm self-propelled gun. This was a prototype artillery silencer at Bundeswehr Technical Center 91 in Meppen.
"Since the universal use of noise suppression systems for tube weapons of the German Army for training purposes is inconceivable due to the high system mobility frequently demanded, the aim of the study was to develop effective muffler systems for a few very problematic cases".
In other words, the neighbors bitched that the Germans had an artillery range in their backyard.
Hey, do you want to be safe or do you want silence while watching re-runs of the A-team? Picky, picky.