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
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The central goal of STANAG 4157 is to mandate a formal process for confirming and documenting that a fuzing system is safe for personnel and "suitable for service" in all expected environments—from manufacturing and storage to transportation and deployment. stanag 4157 pdf
The agreement references a broad range of environmental and functional tests to ensure munitions do not inadvertently initiate. NATO - STANAG 4157 - Standards | GlobalSpec While STANAG 4157 is the "covering" agreement, the
Formally titled "Method of Test and Requirements for the Evaluation of Small Arms Ammunition for Use in NATO Forces," STANAG 4157 specifies the standardized procedures for testing the safety, performance, and reliability of small arms ammunition (calibers up to and including 14.5 mm) across all NATO member states. NATO - STANAG 4157 - Standards | GlobalSpec