Systematic effect in hadron mass calculations

In our attempt to reproduce recent work by Hamber and Parisi we have discovered some important aspects of Monte Carlo calculations of the mass spectrum of lattice QCD. In particular, we find that, for typical values of the input parameters, the hadron propagators reach their asymptotic form only at a lattice distance which is larger than that available in previous calculations. This will have some numerically important effects on the results. We also suggest the use in certain cases of nonperiodic boundary conditions which can increase the maximum available distance on a given lattice