I am loading the 88 ELD's to 2.280". Seems to be the max length my magazines will allow, maybe could go a few thousandths more. I have two 6.8 SPC mags, one is a Barrett and the other is an ASC. Both worked well at that length.
I did try five rounds at 2.346" feeding them into the chamber singly. According to my crude measurements, that length should be .005" off the lands in my barrel. But that group was between 1.5" and 1.75" at 100 yards.
Once I find that best load, I will move out to 500 yards. Don't have access to 1000 yards yet. There is a club about 20 minutes from me that has a 1000 yard range, but you have to be a member to use it, and the membership list is currently full. Going to try to get on the waiting list.
When I completed my load testing I had 10 rounds of the RE15 25.0 grains left. I loaded up the mag, set the scope to the setting on my Strelok Pro app for 300 yards, and hit a 12" steel plate at 300 yards all ten rounds. And that was not precision aiming, just placing the crosshair somewhere on the plate and squeezing the trigger. So that load and the PowerPro 2000 MR look pretty promising for longer distances.