7mm rem mag is what I use it may be a little overkill but you don't have to track the deer very far they stop when you hit them.

.308 drops them dead in their tracks

12 gauge

I have used as small as a .223, but now that I have the .45-70, I don't use anything else. The big thumper is addictive.

30.06 - it's all I have

Oh yeah, 12 gauge too.

I used a 7 mag for the past fourteen years, I just sold it to buy my second 260 Rem. Last year I got the Model 7 cdl 260 and this year I got the
Rem. 700 CDL SF Limited 260 with a Zeiss 4.5-14x50. I just couldn't see using the mag any more when most of my shots are under 250 yrds.

I use a .30-06 w/ 165 gr. Hornady ammo or a 7mm-08 w/ 140 gr. Winny BST's

If I'm hunting down where I live, I have to use shotgun...Rem 870 w/ rifled barrel and Hornady SST's slugs.

Actually almost any centerfire rifle from .24 to .45 caliber will work just fine. I have seen deer shot with just about everything under the sun. One thing that is not necessary is a magnum. People argue that they need them to "reach out there", but most of those people have no business shooting at extreme ranges. .243, .260 Remington, 7mm-08, .30-30, .300 Savage, .308, .30-06, .35 Remington, .375 Winchester, .444 Marlin, .45-70, and the list goes on. These deer are simply not armor plated and it really comes down to shot placement....

i bought a 300 win mag for the same purpose you described. I have a bro-n-law in CO, so we're planning on some elk in the near future. I have had my 300 for 2 seasons, killing 3 deer with it. It is a little overkill for whitetail, but with good shot placement, I've lost little meat and there is little tracking. IMO shot placement is the key. (If you don't mind the recoil) I bought the 300 because I can not afford 2-3 different rifles depending on where I'm hunting.

However, all considered, I am a fan of the 25 and 30-06. The 25 is hard to beat for long shots...and the 30...well everyone owns one...there's got to be a reason behind it.