I've used the 6.5 x 55 and the 6.5 x 284 to take about a dozen elk and witnessed maybe another half dozen taken with the 6.5 x 55. I have used the 130 vld, 130 accubond, 140 bt, 123 scenar, and 120 ttsx. Had great results with the 6.5 on elk. The 6.5s are more than adequate for the types and distances of shots I opt to take and kill very cleanly, at least compared to the other dozen chambering I've use to harvest elk. Headstamps don't limit the types of shots I take but ethics often do. The only 6.5 I caught was a 130 accubond in a wolf taken at about 30 yards.
This doesn't surprise me much. Various tests with big bore cast bullets have shown that faster often results in less penetration than slower. I've seen this in my own tests on water jugs where really slow bullets out-penetrate faster ones. Some examples from my testing:
# jugs // velocity // load
12 // 1167fps // .458" Lasercast 350g
9 // 1812fps // .458" Cast Performance WFNGC 460g
9 // 1554fps // .458" Speer African Grand Slam Tungsten Solid 500g
8 // 2147fps // .458" Speer JFN 350g
7 // 3100fps // .308" Barnes MRX 180g (tungsten-core predecessor to the TTSX)
6 // 2189fps // .458" North Fork FP 350g
6 // 2247fps // .458" Speer UCHP 300g
5 // 2230fps // .375" Hornady FN 220g
4 // 2390fps // .375" Sierra FN 200g
1 // 3650fps // .224" Hornady V-MAX 40g
Granted, there are no apples-to-apples comparisons there. Nevertheless the slower 1167fps 350g hardcast out-penetrated both the 1812fps 460g hardcast and the non-expanding 1554fps 500g Speer AGS, 12 jugs to 9.
