I know this thread is a bit old, but I found it useful so I'll add my 2 bits. I was concerned that my velocities were too low, but after seeing these posts I think I'm right where I need to be given the short barrel.
I have a 6.5 CM in an AR-10 platform, 18" barrel, shooting with Omega can.
Loading Hornady brass, H4350, ELD-Match 140gr, CCI 200 primers.
My charge weights and velocities on a recent trip to the range were as follows:
40.0 2510
40.2 2496
40.4 2510
40.6 2554
40.8 2554
41.0 2554
41.2 2574
41.4 2564
41.6 2594
41.8 2599
42.0 2614
42.2 2609
42.4 2666
42.6 2650
42.8 2704
Found good nodes around 2554fps and 2600fps. Feeding from mag so can't seat to lands, however tweaking the seating depth led to a nice group at 2554fps. Going to try 2600fps and see if it yields equally good results.
Hope that's helpful to someone!