Not the same as a metallic cartridge/primer set up. The primer in this instance is firmly seated and surrounded by the base of the brass (steel/aluminum) cartridge and must be physically deformed in order to create the friction/compression necessary between the primer cup and anvil to ignite the lead styphnate/barium nitrate (or whatever other specific chemical compound) primer.
If you don't physically deform the primer, then the primer does not ignite. And that deformation can only happen from one direction, within a very narrow angle of attack.
This is not, of course, to day that modern primers will never ignite under any other circumstances. However, with literally trillions of rounds of modern ammunition having been manufactured and used since their inception, such events are exceedingly rare indeed. Even rarer, perhaps to the point of non-existence, when talking about simply loading a weapon. Probably the closest would be an example of ammunition "cooking off" in a weapon that has been used so much that the receiver has become very hot...to the point of glowing, even. Outside of military weapons being used in combat, this scenario would be rare, indeed.
