I made the mistake of mentioning this to our safety and risk guys in the guise of "I want a can, if the boss says no will you backstop me from an Occupational Health perspective to justify my desire?"
What he heard was "any real world use will likely result in repeated noise impulses over 140dB". He then wanted to know why hearing protection wasn't mandatory all the time. IIRC 140dB is the OSHA threshold for immediate hearing damage. For those guys hearing protection is mandatory for the guys running lawnmowers and leafblowers. It is their job to protect us from the hazards of our job, and save workman's comp and disability claims. He nearly derailed our patrol rifle program until cans were standard, required equipment. It took a bit of tap dancing to get him to back down. Chiefs don't like being made to do things by anyone, let alone a patrolman and firearms instructor using an outside regulatory body in a scheme...We also face a better than even money likelihood of deploying indoors. I had to accept good rather than going for perfect.
We didn't get cans till 11 years into our program. We hired a State POST Master Instructor with a lot of real world tactical experience who lobbied for them. Then he refused to issue them until we had a policy in place. 15 months later we have three cans fielded (used to be four till a former 0311 and 25+ year police officer misthreaded his can....) more than a dozen of them are sitting in an office, waiting to be issued, with not a little hypocracy and sour grapes going around.
pat