A series of blast tests is described in which blast impulse is measured by an impulse plug technique for spherical explosive charges. In this approach the reflected blast impulse delivered to a hardened bullet-shaped steel plug is determined from a measurement of the plug terminal momentum. Plug velocity is measured by a high-speed, high-resolution video camera operating at 20,000 frames per second. Spherical C4 charges are studied for varying charge weight and charge-to-plug standoff distance. Tested standoffs include the demanding near-field blast zone within which pressure measurement by transducer is extremely difficult or impossible. Results are compared with previous studies made using transducer and impulse plug methods for both C4 and Pentolite charges. The present data for half-pound C4 charges are in good agreement with much earlier impulse plug data for spherical Pentolite in the near-field region, however, differences of up to 26% are noted with more recent transducer measurements for C4 just beyond the near-field zone. Test results are also compared with hydro-code simulations of the plug response.