We present molecular-dynamics simulation results for the equation of state of one-component fluids containing freely jointed hard chains of lengths 2, 4, 8, 16 and 32, and compare these results with the predictions of the generalized Florydimer theory. In addition, we present the predictions of a modification to the generalized Flory-dimer theory which uses accurate values for the exclusion volumes of hard chains. Using a Monte Carlo integration technique, we obtain the conformationally averaged exclusion volumes, mean-squared radii of gyration and mean-squared end-to-end distances of isolated freely jointed hard chains of lengths 3, 4, 5, 6, 7, 8, 15, 16, 17, 31, 32, 33 and 64. This modification to the generalized Flory-dimer theory improves the agreement with simulation results for the longer chains at high densities, but has negligible effect at intermediate densities.