Wow, Mechano sets, I had a couple of those. Also had Big Jim and a couple of GI Joe's. One of them had a beard so I shaved him, then drew it back on with pen.
Never blew up my action figures with firecrackers, but I used to shoot them with my pellet gun. Same with my old car models. Shoot em up then light them on fire.
I do remember pulling out some old shotgun shells outta the pail where Dad stored them. We took them to the pond and tryed to pry them open. In hindsight, we were damn lucky none of them ever went off.
Pennies on the train tracks all the time and we also walked across the train tressel. It was about a 1/2 mile long and a 100 feet or so high. We used to put our ears to the tracks to see if a train was coming. Don't know if that works, but we never encountered a train.