What could prevent a shell from aligning with the magazine tube opening?

A bent carrier can impede the smooth feeding of shells into the chamber, leading to misalignment with the magazine tube opening. The carrier is responsible for lifting the shell from the magazine tube and presenting it to the chamber. If it is bent, the shell may not rise to the correct position, resulting in a failure to align properly.

In contrast, an empty chamber would not prevent alignment, as there would be no shell present to misalign. A faulty firing pin impacts the firing mechanism rather than the feed system. Excessive recoil might affect performance but would not specifically cause a shell to misalign with the magazine tube, as it primarily relates to the forces exerted during firing rather than the feeding process itself.