Go forth and slay stuff, they work. I load them in 6.5x284, sometimes in 6.5x47 and plan on trying them in my 6.5-300WSM. Last year a buddy borrowed my 6.5x284 for most of the season. He killed 5 deer with the sst all DRT or within 40 yards.
I admit that I know just enough to be dangerous.....but dangerous at ever extending distances.
Though I can't vouch for the 129grn 6.5 SST, the 140grn shoots sub 1/2MOA from my 6.5x55 Swede and kill effectively. 2 Mulies fell to this rifle this fall at 252 and 148 yards. I chose the bullet after witnessing a friend down a big Mulie buck at 75 yards with a .308 and 165grn SST, busted both shoulders and found the bullet in a perfect mushroom just under the hide on the far side. That bullet retained 70% of its original weight. I wouldn't hesitate to shoot an elk with my Swede load. I think the SST is a winner, equal or damn near bc to the Amax and Interbond only cheaper to shoot.