Periodically we have some training and it shows the results of the pipe bomb going off in the makers hands.
Black powder and smokeless to a lesser extent is pressure sensitive. One grain of black powder in the threads might be enough to detonate it.
note the substance in the photo. It appears to be beige or tan in color and not the shiny black appearance I think of as black powder.
One wonders if wondering what the substance is on line gets you on the list