The effect of charge size and geometry has been investigated. A series of experiments have been performed with explosive masses up to 2 lbs. in which the effect of internal blast performance in a rectangular structure was measured. Performance was based upon pressure measurements at multiple locations within the structure. Confidence in the measurements was achieved with the use of multiple gauges at the same location. The explosives tested contained both ideal and non‐ideal compositions. A correlation was determined that allows for research size samples (< 100g) to be compared with greater sized charges. © 2004 American Institute of Physics