Full‐scale explosive blast testing is too involved for routine testing of blast protective helmets. In contrast, gas‐driven shock tubes are cost‐effective, do not require high explosives and generate repeatable shock waves, making them, at first glance, appealing for routine helmet testing. However, previous studies have demonstrated that the flow field outside a shock tube does not represent that which is generated in a free‐field blast test. The objective of this paper is thus to demonstrate how this flow field difference affects headform response, given that standard methods for helmet impact attenuation involve surrogate headforms and corresponding acceleration measurements. To that end, a headform instrumented with linear accelerometers was subjected to both shock tube (headform outside the tube) and free‐field explosive loading. The explosive charge and standoff distance for full‐scale explosive blast testing were selected to replicate static blast parameters previously set for the shock tube testing. Preliminary findings indicate that matching peak static pressure and peak impulse with a headform outside a shock tube does not appropriately reproduce free‐field explosive blast headform inertial responses in terms of acceleration, velocity and excursion time histories.