I made a "blanks" once for a fun shoot. I borrowed the idea of shooting ballons from the CAS mounted folks. Having not a single horse, we put a bunch of ballons on posts and shot them from riding lawnmowers. The recipe was much like yours, pretty much a case (357) of grits over a small charge of Titegroup, with a cardboard wad crimped over the top. Never tried it on any bugs, but one of the shooters wanted to see if he could shoot the string of five ballons from the side, maybe 10 feet to the furthest one, and they all popped easily. I shot one blank straight up and you couldn't see any grits come down, so it must have had a little more velocity than I had hoped for. By the way, burnt grits smells funny.