Faulting on {211} planes has been reported in filings of many bcc materials based on differences in the broadening of various peaks in the x‐ray powder pattern. These experiments have been repeated in this work using (a) recent techniques for correcting for various experimental errors and (b) new derivations of effects of faults on other planes. It is shown that the mean‐square strains⟨&egr;L2⟩are generally inversely proportional to the distanceLnormal to the reflection planes. As a result, it is possible to separate effective particle‐size (including faulting) and elastic strains from several first‐order reflections, rather than with multiple orders. With this approach, the results indicate that there are no faults produced by filing in Fe, &bgr; brass, and Mo&sngbnd;Re alloys. For Nb there are faults on {110}, and the concentration varies inversely with the interstitial content.