What is the definition of the "material developer item manager"? In any given Army manufacturing program, who or what role/position is responsible for originating the QDR from a TIR?
In the context of your question involving Aberdeen Proving Ground (APG), APG would not usually be classified as either a material developer or item manager. Instead, APG the test service provider.
The material developer is the organization that is responsible for research and development (R&D), production, and fielding of a new materiel system and is usually the Program Office.
An item manager is normally designated through the Program Office to manage the end-to-end support of a system, subsystem, or component of the system such as an engine, transmission, cable, etc. and can include various organizations to include Defense Logistics Agency (DLA), depots, within the PM shop, or related support command such as TACOM supports most of the repairable parts of the ground vehicles in Warren, MI.
If APG is conducting live fire testing of your product, it is standard a process that the requesting organization defines and funds their efforts to conduct the testing, capture data, and enter Test Incident Reports (TIR) in the database designated by the requesting organization. As most test organizations are fee-for-service, your organization should be able to define, fund, and obtain the TIR information from APG as part of their test service.
Once the TIR data is received from APG, normally the Production and Quality Management (PQM) personnel within the Program Office develop the Quality Deficiency Report (QDR) that is then used to work corrective actions on the design or production of the item under test with the prime contractor.