Full magnetic hysteresis loops, obtained by underdamped discharge of a capacitor through a solenoid, were used to study loop distortion produced by eddy currents, protracted or delayed flux changes, and instrumental errors. Pulsed field loops obtained for γFe2O3 powder with 14 000‐Oe maximum field closely overlapped loops obtained statically with one‐tenth this field amplitude. In contrast, an apparent coercive force of 110 Oe was obtained with the pulsed field method for a sample of 0.158‐cm‐diam iron wire having a static coercive force of 3.6 Oe. Almost two‐thirds of the observed coercive force was attributable to eddy currents. Instrumental errors were less than 10 Oe and the residual coercive force was identified with the protracted flux change which has sometimes been attributed to magnetic viscosity in iron. Instrumental difficulties involved delay, distortion, or imperfect integration of high frequency components in detector coil signals, cumulative integration errors associated with low frequency components from nearly saturated specimens, and pickup. The detection system described is also suitable for quasistatic (slowly traced hysteresis loop) measurements.