First, a derelict cylinder would have the contents unknown because the labeling was gone or the valve was corroded or damaged such that the cylinder could not be safely be emptied. Typical contents would be lab gasses with some inert such as nitrogen and argon and others oxidizers such as oxygen, some explosive such as hydrogen and acetylene and some poisonous such as carbon dioxide. Also never knew with certainty if a cylinder was full or empty.
The cylinders were shot from about 150 yards away. Most would be non-dramatically turned into a cylinder with a hole in it. Acetylene and hydrogen tanks would have some flame, maybe explode and sometimes go rocketing along the ground or spinning in a circle. You absolutely do not want to be anywhere near any cylinder or tank shooting at it. Dangerous plinking.
Absolutely!
I don’t know if you have ever seen this video, but it is a fire at a propane storage facility next to a highway:
https://www.youtube.com/watch?v=n85R3OXK3bs
Heh, nobody closed the highway down, and if you go to the 5:40 mark and begin watching, you can see the flaming canisters landing on and around the highway, almost as if there was someone saying “Up 50...down 10...Straddle! Fire for effect!”