Karl from InrangeTV has had a carbine detonate while loading the tube mag because he just dropped them down the tube instead of inclining it like Tactical Lever said in post #599.
Okay, just spitballing here...When a rifle is fired, the cartridges in the tube are, by their own inertia, held in place while the gun recoils backward. They try to move forward with respect to the gun; just like a scope slips "forward" in loosely tightened rings during firing as its inertia attempts to keep it stationary. They will be slightly compressing the magazine tube spring with each shot. The spring immediately bounces them backward to their original position in the tube. How much would they actually move? A tiny fraction of an inch? How much energy could be applied to the primer in this case?
Wben inserting cartridges into a front-loading tube mag, I've always held the gun at an angle and allowed them to slide down into the tube. In this case the cartridges are moving much further, but also much more slowly. Again, how much energy is applied by the bullet tips to the primers?
When "Karl"...I have no idea who he is, but he's obviously an expert because he makes videos...loaded his rifle did he drop them down the tube vertically as an experiment...or is that the way he typically loads the thing? Those cartridges are falling the full length of the tube, and doing so at more-or-less free fall velocity, less the incidental friction they would encounter from brushing the tube walls on the way down. Is he intentionally trying to cause a primer ignition? Or is he just stupid?
We are handling devices that use springs held in compressed states by delicate triggering mechanisms, that are then released to intentionally ignite flammable compounds which in turn develop near-instantaneous dangerously-high levels of pressure...to propel a projectile through a barrel at high velocities...and we are doing it for fun! Of course there is an inherent element of danger; the degree to which individuals accept this varies.
We're way. way off base from the original intent of this thread; apologies to Henry for the massive derail.