I'm a little confused as to how the cartridge discharged in the magazine. With firing the rifle would move rearward. Cartridges not held tightly in the magazine would have their own inertia, which would mean that the rifle is moving past them. Relative to the rifle the cartridges are moving forward, potentially banging the points into the front of the magazine. As the rifle's rearward movement slows with the recoil being absorbed the cartridges would then tend to move rearward relative to the rifle but it would seem that the difference in forces would be much less and spread over more time. So, as noted I'm not understanding how a cartridge that is a quarter inch shorter than the magazine well could be fired as a result of the rifle firing, particularly if the primer is seated flush or lower than the cartridge base and the magazine wall is smooth.