looking at three different cal for white tail hunting. they are as follows, 6mmx284, 6.5x284 and 257 roberts. Input would be helpful.

The 6.5x284 has the heaviest bullets avaialble as well as a little more frontal area than the rest of the 3 an sufficient velocity so it should kill a litte better. Personaly I have a soft spot for the Roberts and with a 120 NP at a sedate 2820 fps I'd be very confident that it would kill any whitetail.

Mark

Couple of questions. Do you reload? What range will you possibly have shots at? Lastly do you already have rifles in these calibers or are you building?
Without that information, all will work for whitetails, but if I was picking one I would go for the 257 Roberts, that is unless I was shooting longe range then I might opt. for the 6.5-284

The 257 Roberts, which I love, is a really sweet little whitetail round, but for an all around deer rifle the 6.5x284 is more versatile. It shoots very flat and has a little more bullet to it. The 25 caliber bullets are my personal minimum for deer.

The 6mm's are varmit rounds in my opinion, not suitable for deer.

Get a good 270 Winchester. In the field you will never see the difference. Just my opinion but I just do not undertand hunting whitetail deer with a wildcat caliber.

257 Rbts or the 6.5X284 will both reliably down a whitetail. I use a 260 rem. and have had three one shot kills recently with 100 gr. hornady handloads.

Another vote for the 6.5x284, splendidly accurate round, and about perfect medicine for whitetail size game.

Having said that, I will second the post about the .270 Win!