I have never shot a sable with my 6.5 Creedmoor, but I killed a good number of waterbucks with this controversial caliber.
A big waterbuck bull is a tough animal and a premium bullet is definitely more suitable than a classic cup and core bullet.
Last year, I shot a big bull in South Africa with an ELD-X 143 gr. He was full broadside and I hit him in the shoulder.
Thanks to the slope, the animal ran 200 meters, jumped above a cattle fence and died in a thicket. With such a perfect shot, the animal was able to cover a good distance but I'm not really surprised because even with bigger calibers, like the .338 Lapua magnum and the .458 Lott, I saw how they can soak up these big bullets before going down.
When we carved it, I noticed the bullet didn't even reached the opposite shoulder and blew up in the vitals.
This ELD-X works well on kudus and nyalas, as well as smaller games, but it is too soft for being reliable on heavier games.
I had the oppotunity to shoot another big bull during this trip and this time, I switched the ELD-X against a TTSX 120 gr. It did a good job and went trough. The animal didn't go far and stopped quickly. I finished it off with another bullet just behind the ear.
In the past, I had a good success on waterbucks with Swift Scirocco 130 gr, Barnes TTSX 120 gr and also the good old Hornady Interlock 160 gr.
The last bullet is not a bonded core, but it keeps a good weight retention and it provides a deeper penetration than the ELD-X. For sure, it's quite weird to see it loaded on a 6.5 Creedmoor case, but at 2500 f/s, it remains a good option for shots at short and medium ranges.