Got two Sako Trg-S, a 30-378 and a 338 lapua. Used sako optilock mounts and rings on both. The 30-378 has been on two elk hunts now, without a problem with the mounts. One was a horseback hunt.
The 30-378 has a hair line crack on top of the tang. Kinda think that when the receiver was bedded, that area was not properly releived. This was last year, repaired it and its held up to date.
Also have a Sako AV in 375 H&H, again with the optilock mounts. This has survived two trips to AK. Checking my zero upon my return, she was right there.
Plus another AV in 416 Rem, just in case that trip to Africa becomes a reality.
I consider purchasing these Sakos to be one of my better fiream investments.