Sand blast gun

I have a Brut 50# blaster, made in Ohio. I have found that with the harbor garbage one I had, and the made in USA one, you can’t shoot anything bigger than fine grade media. I tried lots of stuff, a reverse male air hose end, changing this and that, and both will only work with the fine using the 1/8 tip. I did my whole car with it. Little at a time of course. From time to time the good one will still clog, but you’ll have that