If you are looking for the full document, it is officially titled and is distributed as AOP-4157 . STANAG 4157 : 2017 | Safety, Arming & Function System
Applies to all SAF systems, effectively using the terms "SAF System," "Fuze," and "Fuzing System" interchangeably within the document. Relationship with Allied Ordnance Publications (AOPs) stanag 4157 pdf
The US does not directly adopt STANAGs but uses “MIL-STDs” that are harmonized with them. – “Test Procedures for Small Arms Ammunition” – is aligned with STANAG 4157. It is unclassified and available through the DoD Acquisition Streamlines Information System (ASSIST). Download is free for .mil and .gov users ; others can access via DTIC Online. If you are looking for the full document,
While STANAG 4157 is the "covering" agreement, the actual nitty-gritty test procedures are often found in Allied Ordnance Publication 20 (AOP-20) . Why Interoperability Matters – “Test Procedures for Small Arms Ammunition” –