+1
Exactly as Mr. March, Mr. Jordan, and several others have said.
When a revolver is fired, the firing pin drives the cartride fully forward into the chamber, and the primer ignites as the hammer rebounds.
Pressure inside the primer pocket raises instantly high enough to unseat the primer.
Without any chamber pressure to drive the case back, the primer remains unseated, and ties up the gun.
If you drill out the flash hole as recommended by Bill Jordan, there is not enough pressure in the primer pocket to unseat the primer.
A more modern example can be seen in the lead-free ammo now being loaded.
Some of it has nearly 1/8" flash holes to lower primer pocket pressure and prevent gun damage from the primers backing out forcefully with the more viloent "lead-free" primer compound.
There were problems with breach-face peening from the backed-out primers slamming into them so hard until the flash-holes were enlarged to prevent it.
rcmodel