The total punchthrough probability of showers produced by negatively c
harged pions of momenta 30, 40, 50, 75, 100, 200 and 300 GeV/c, has be
en measured in the RD5 experiment at CERN using a toroidal spectromete
r. The range of the measurement extends to 5.3 m of equivalent iron. O
ur results have been obtained by two different analysis methods and ar
e compared with the results of a previous experiment.