Dents in the case shoulder can be caused by all of the following except:

Dents in the case shoulder typically result from issues that impact how the case is formed and handled during reloading and resizing. An improperly trimmed case is more likely to cause issues related to length, but not typically dents in the shoulder area. The act of trimming focuses on the overall case length rather than the shoulder profile, resulting in less relevance to the formation of dents.

Excessive lubrication during resizing can create a situation where the case is too slick, leading to slippage within the resizing die which might result in pinching and denting. Incorrect resizing can similarly lead to dents if the die does not properly align with the case or if it fails to resize evenly. Old brass can also be more brittle, making it more susceptible to dents or damage during handling or resizing procedures.

Therefore, while all other options focus on aspects of the resizing and handling process that contribute to dents, improperly trimmed cases are less linked to the formation of dents in the shoulder, focusing more on overall functionality.