Cannelure

[3] The lubricant reduces metal fouling by lead that is rubbed off the projectile and onto the bore by friction.

[6] It is also a concern in guns with tubular magazines, such as lever-action rifles, as the column of cartridges in the magazine compress the feed spring that can bounce during recoil, thereby slapping the cartridges against each other's noses.

Dropping a rifle with a tubular magazine can also inflict a damaging inertial pounding on the noses of the cartridges within it.

Revolvers that have heavy recoil (and even some that do not if used with poorly crimped cartridges) can have their bullet move forward out of the case.

[4] Bullet setback of .1" can increase pressure beyond safe limits and possibly cause a catastrophic failure.