Now I have the good fortune of living in Colorado and being a fairly serious elk and mule deer hunter. I have killed close to 20 of each animal and been in on about the same number with other hunters shooting.
Lets get a couple of facts strait, first elk are increadibly tough and demand far more respect in killing one than any thin skinned deer does. They are not super beasts that wear bullet proof armor, but they soak up bullets and go a long ways befor they die. I have broken the front shoulder of a elk at 200 yards with a 300 mag and 180gr Nosler Partitions and lost the blood trail and the elk 6 miles and 2 days later! I slipped the bullet through the shoulder and I think it exited the front of the chest between the front shoulders did not clip any vitals. I have shot with the same gun a 5x5 through both lungs and the heart and had it run over 1/2 mile before falling dead on a hill side so steep I had to hold on to trees to stay up right.
One of the best elk hunters I know killed the first 8 elk he ever shot with a .243 before he was told it was not a elk rifle!? He was a rancher who knew how to shoot, picked his shots at quiet elk (not spooked and pumped full of adrienalien), and they die by god.
What I am getting at is this shoot a elk in the vitals, at a reasonable distance, with a tough, well constructed bullet and they will die period. Hit one baddly and you will find yourself in a world of hurt and find out why elk have the reputations they do.
Why do people want the heavy stuff when just as you say you only need 3 feet to go through a elk? Well what happens when you mess up and your bull of a lifetime is wounded and about to walk into the dark forest 100 yards away at a bad angle and at last light? You need all the help you can get to pound through a rear ham to get to the vitals! Experienced elk hunters choose the very best guns and bullets for elk not for the ideal conditions but for the unfortunate conditions where the chips are down. I hunted the last two years with a .45 colt with 335gr LBT bullets at 1250 to 1300fps and feel I want everything that load will give me.
John Linebaugh has told me on several occations that at 1200 to 1300 fps you will get all the penatration that the bullet will give you, going faster does not get any better results. So the idea is go to the heaviest bullet you can get you gun to shoot at that speed, practice a lot and PICK YOUR SHOTS.
I love elk, eating, hunting, the lore of them etc. You owe it to a elk to respect it, give it everything you can, and kill it cleanly or don't pull the trigger. For the record I have passed on serveral opportunities with my pistol letting down the hammer unfired at least 5 or 6 times because conditions were not right, angle to much or the distance further than my self imposed limits (40 yards off hand and 75 with a good rest). The elk in my freezer died to my .338 with 230 grain Failsafes at last light on the last day, last year. But I am going wheelgun or nothing this year.
Good luck with your hunts