I believe the Pappas one piece rest is the best choice for 50 yard, rimfire bench rest. That said, I use a rest built by the Altoona, PA technical school and an Edgewood rear bag. I can compete with this arrangement but do not win.
Rifle and ammunition make a major difference in the benchrest game. I am currently using a Kimber 82G with Federal Gold Medal Ultra Match. Again, I can compete but do not win. If you want to have a shot at winning, then you will have to get a custom action with a really good barrel, a well bedded stock and a good rest. Then you will have to find the ammunition that your rifle likes and practice like everything to learn how your setup performs under different environmental conditions.
.22 LR bench rest is a lot of fun. I think it is more difficult than center fire benchrest because you cannot control the quality of your ammunition. Good ammunition is tough to find on a consistent basis. I strongly recommend that you attend a few matches and watch. My club has an informal shoot on a monthly basis. We provide the rifle, the rest and good ammunition for newbies to experience the game. If you are in the Dallas, TX area, come shoot with us. Advice and equipment is available for free for newcomers.
Cort