Matt Stoller looks at the ammunition shortages.
https://www.thebignewsletter.com/p/why-america-is-out-of-ammunition
A result of consolidation of the manufacturing base.

A few references to a GAO report on DOD procurement. The DOD has TWO (2) people who look at mergers and other changes of ownership - there are roughly 400 of those a year. Basically, no oversight.