John, you about summed it up....
Shot placement is the key to success w/any round.
I do feel that the 6.5s have a very low to really I never hear of them- failures, on deer, vs. say 6mm rounds. Obviously 6.5's are usually stuffed w/longer heavier bullets, but more importantly of proper construction.
The 6mm's were developed as a 'dual-purpose' varmint-deer capable rounds, and they do very well with that, w/correct bullet choice and placement. Use the wrong bullet, combined with poor shot placement and then you open a can of worms.
I have shot deer with 70gr TNTs out of both a 6BR and 243 at 3400 and 3500 mv respectively, and was successful because I knew the limits of the bullet, and chose a broadside lung shot and neck shot respectively. Both dropped quickly
Yet as Jeff can attest, the lighter bullets can and do kill, as all bullets will, some are just more forgiving, and when it comes to bullet selection for big game, the overwhelming majority of bullets in 6.5mm are for larger game, and that pretty much applies to most calibers larger as well.
In 17-25 cal, you have many more varmint bullets, but as we have seen in the past few years, premium bullets in smaller calibers have deadly results on game such as WT and Mule Deer. I would be as bold to say a 6mm, whether a BR or 240 Weatherby and all in between, using say an 85 TSX, 90 Swift, or even the fairly stout 95 BT designed for larger game, have a record of success rivaling standard c/c bullets in 25 cal, 6.5, and 7mms that often use 115-140gr bullets.
What beauty lies in the 6.5s is of the few varmint bullets available, you can usually find one that is accurate and explosive for that duty w/in these: 85 Sierra, 90 TNT, 95 Vmax, and 100 Sierra HP. The Hornady 100 SP is capable of varmints but deer as well as Seafire can attest.
If I wanted ONE bullet to do it all, a 120 ballistic tip and 130 NAB would be my pick. The latter would not be as explosive on varmints but the BT would not hold together quite as well on larger game. Pick your poison, but if I wanted to have ONE Load to do it all, I would pick a mid range bullet wt. that was foremost very accurate, but secondly holds up well if a bad angle is taken on deer. Varmints on a 6.5 menu would most likely be coyotes and similar game to my thinking, but I would not be opposed to using some light wt. bullets on prairie dogs and similar game. Those lighter wt. bullets would no doubt be safer and that is a consideration in many places and situations.
To my thinking, the 6.5 options of 85-160 gr give their owners a plethora of choices for most any need in NA. No doubt a 200 partition in a 30/06 is 'more gun' on the largest game, but a good 140-160 gr will often penetrate as well and do the deed if the owner does their due diligence. Less recoil which improves the shooters skill offsets what some may say a lack of surplus kinetic energy.
Stats alone never killed anything....
