Dodger mentioned 3/4 sch 40 pipe. This could work well. For standard pipe the I.D. is .824" and O.D. = 1.050". It would be easy to put the material in a lathe and turn it down to 15/16" but it will have a pretty thin wall thickness. You can also buy 15/16" tube with an I.D. of .772" that you can simply cut to length.
http://www.aladdinsteel.com/products...amless_tubing/ Use a tubing cutter for a square cut every time.
Tips: Pipe size is measured from the I.D. Tubing is sized from the O.D. Usually the dimensional requirements for making tubing is much tighter than for making pipe. Tubing may be more expensive than pipe but it will also need less machine work.