Abstract Rocket propelled grenade (RPG) shaped charge attack threats are of particular concern for Insensitive Munitions (IM) development. In response to these threats, the U.S. Project Engineering Office for Ammunition (PEO Ammo) worked with ARDEC to develop a highly reproducible and well characterized standardized 81 mm shaped charge jet initiation test configuration. This test was adopted by the U.S. DoD for RPG threat testing as specified in MIL-STD-2105D and is completed as per STANAG 4526. Recent U.S. Insensitive Munitions shaped charge initiation attention has been focused on realistic smaller shaped charge threats. STANAG 4526 discusses standardized threats related to “Top Attack Bomblets” and SCJ with “Characteristics of 50 mm Rockeye”. As a representative shaped charge for smaller size threats than the RPG, the 50 mm Rockeye munition has been commonly recommended for testing. However, recent testing of the 50 mm Rockeye munitions has shown a large undesirable variability of jet tip characteristics. This large variability in jet tip characteristics would be consistent with a large variability in munitions response to the 50 mm Rockeye jet attack. Additionally, it has become clear that this shaped charge does not represent a commonly observed threat. For this reason, an effort is currently underway to identify a dominant smaller shaped charge threat and to develop a surrogate small shaped charge threat test configuration that provides very reproducible jet characteristics. The result to date is that 40 mm grenades have been identified as a dominant smaller shaped charge threat and a surrogate consistent in approach with previous efforts has been designed.