@ceruttif
I reduced the interaction length by 1E-2 in my LAM-BIAS card. I hope this scaling factor is reasonable and suitable for my work.
You put it in the wrong place: it should not apply to mean life (referring to particle decay, which is meaningless for protons), rather to interaction length \lambda, as you wrote. To judge if it’s reasonable, look at the beam particle \lambda in PbBi as printed in the .out output file (search for the respective material table) and compare it to your target thickness (then one should also consider the proton range and energy loss in the target material).