I love reading debates about rifles brands, models, calibers, bullets, etc. from people, many with a lot of enthusiasm. I'm no expert, but the order of importance for making a clean kill might be as follows:
1. The nut behind the trigger - by far the biggest factor -- includes knowing the capabilities of yourself, the rifle, and the cartridge, knowing the range, knowing when and when not to shoot, good shot placement, etc.
2. The bullet design/composition
3. The cartridge/caliber and its capability (energy, "knockdown power", mass, diameter, etc)
4. The rifle brand, bolt vs. auto, synthetic vs. wood, blued vs. stainless, trigger feel and pull
I'm probably missing many things here. Maybe #2 and #3 should be switched?
One of my pet peeves that is down the list is trigger pull -- I hate rifles with heavy triggers -- which many manufacturers felt the need to make for a number of years. The last few years they have come back to sanity a bit regarding trigger pull.
Obviously, there are a wide range of bullets, cartridges, and calibers that will work for most situations -- and #1 is so far above, the others pale in comparison. With the majority of deer/elk shots well under 300 yards -- #1 is the overriding factor. When it comes to longer distances, a rangefinder is required, as many people estimate distances like they estimate fish weights

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For a highly skilled person at long range -- some of the subtleties become more important.
Even so, it's fun to read about people's opinions of rifles, etc -- as people are different, with different applications, and like to have the "best" gun -- both functionally and aesthetically -- that they can afford -- hence so many options. It is great to have those options!
My

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BlindSquirrel