I posted a comment to a similar question but it comment turned out to be in error. It was pointed out that there was no source of carbon. My OOPS! correction never appeared for some reason. I had mistakenly typed fulminate when I should have typed azide. The corrected comment is:
"I would be extremely careful. Many years ago I attempted to prepare mecuric basic bromate by dissolving mecuric oxide in bromic acid followed by neutralizing with ammonium hydroxide. I may have prepared the compound of interest but the resultant crystalline compound was quite shock sensitive and would explode easily. It is now believed to be, or to have contained, mercury azide. Your recipe is likely to produce silver azide. Because of the concentration stated, you might get away with it but be extremely careful, any dried residue could be explosive. "