Sort:  

There's always a small chance of it, the powder is an explosive/accelerant after all, however precautions are always taken.

It's a bit like filling the car with gas, one wouldn't also strike matches, or be welding at the same time.

All brass is collected where possible, it's costly to buy. Sometimes one goes AWOL but that's rare. Like you say, low light or in bushes long grass and sometimes even in dirt and sand, they just seem to disappear. Other than that, no man brass gets left behind.