Wads are probably the most misunderstood component of reloading. Charlie Dells work showed that it is what the wad does to the charge not the wad it self that causes the damage. You have to think in terms of a shaped charge. When the wad is down tight on the powder it shapes the explosion into a “plug” of force that when it meets the bullet’s resistance slams into the bullet base pushes against the side of the case and the chamber. Most chamber rings are not the one time catastrophic type but built over time and a few hundred shots.
Charlie found that a wad left .050” to .100” off the powder leaving the powder to slump was effective in eliminating the shape of the force that did the damage. He found that the slump was most effective when it was positioned to the primer side.

40 Rod