Calculations of the time-averaged solar flare particle density distribution as a function of energy per nucleon and distance from the sun are presented via standard diffusion-convection-adiabatic decelaration theory with a diffusion coefficient independent of distance from the sun. Normalization at the orbit of earth is accomplished via observed track density versus depth profiles in lunar vug crystals. Applying the results of these calculations to irradiated grains from gas-rich meteorites leads to the prediction that if these grains were irradiated in the asteroid belt and if source and modulation parameters have changed little since irradiation, then the track density profile should be 'harder' than the lunar vug profile by about 0.2--0.3 in the index. Within this framework, knowledge of the time-averaged solar particle flux in the asteroid belt allows a quantitative determination of the solar flare particle exposure ages of the grains by comparison with lunar results; previously determined exposure ages (103--104 years) may be somewhat low.