Nate 45--There are so many variables that go into a deer falling DRT when shot, as opposed to staggering 20, or 50, or 100 yards and being DRT, as opposed to scampering off into the next county, that I for one can't see the base of the bullet being a major factor in any case.
If the deer was shot at long range, say > 200yd, the boattail will contribute to a more accurately placed shot. Closer than that, the boattail won't have an appreciable effect on accuracy.
Now, you state
I from my own experience have seen this effect many times and have talked to many other hunters who have noted it as well.
Well, what is "many times?" And exactly how "many other hunters" have noted this in any sort of scientific comparison. Have you been keeping careful records on this over the years?
Forgive my saying so, but that sounds like belief talking, not scientifically valid comparison.
Now, I have no problem with belief. If you BELIEVE that flat bases are going to do the job, then use the flat bases in which you have more confidence. And at normal deer-shooting ranges, it won't make any difference in accuracy. But you'll get better results because you believe you will.
For me, I use boattails. I get one-shot DRT kills when I place the bullet where I should. And I don't when I don't. But I started using boattails when I started reloading, because they slip into the necks of the cases easier!
To each his own.