For a Reo or any bottom feeder
mod, you want a open adapter but you shouldn't need to use an adapter on a 510 Reo. Your attys also need to be open on the bottom too.
Have you tried loosening up your attys on the Reo? Maybe you are tightening too much. They just need to be snug not real tight.
Jump over to Reo sub-forum and start a topic about your problem. They are very helpful and will be able to give you more help and tips than I can. I have never had a problem with the draw of on an atty or carto unless it's been used for a long time without cleaning.