There is plenty of load data on the site. Do a search "260 Rem". Be sure to include the quote marks. Set your range for 2 years. The 250 post limit won't let you get that far back, so once you harvest the first go-round of data, reset the date range of your search parameters to longer than 1 year but less than 2 years. You'll get a big hatful of additional hits--all you'll need.
AOL will likely be determined by you max mag length assuming your rifle is a short action; in which case theoretical maximum length based on the leade may not matter. You'll be stopped out by the magazine length first.
Or use a Stoney Point gauge or candle to determine max cartridge length based on throat/leade, but compare to max mag lenght before loading up a bunch of rounds. Back off 0.050" from the lands for a Barnes X, and experiment with 10-50 thousands for most other bullets, according to group size and pressure signs. Be careful not to seat TSX's, Trophy Bonded or Failsafes (if you have any) to close to the lands. Watch for pressure signs.
