Coal Dragger, do you have links or can you provide the U.S. military’s studies? I’d be interested in seeing them.
I’ve never heard of maintenance schedules corresponding to barrel length. Do you know which branch(es) does that? In the Marine Corps, the maintenance plan is essentially to fix what is broken when it breaks, conduct limited technical inspections and pre-firing inspections prior to ranges and fix/replace any broken/worn parts or other areas of concern, and to clean weapons spotless after ranges/field exercises and during monthly cleanings. Some weapons look like they are “in the white” from having been used and others are pristine. They get replaced when they break beyond repair, not when they reach a certain age. Not saying you’re full of BS, but I have not heard of barrel length having anything to do with maintenance schedules.