Headhunter said:
Some guys on this forum think a 50 is barely adequate for a whitetail, and a 40 will bounce clean off.
I'm not "one of those guys"...and I think that statement over-simplifies and mis-represents the general theme of past .40cal discussions.
I'm fortunate at this stage of my life to have a few calibers to choose from...and while my little .40cal is a tack driver, I'd never leave the house with it for a day of general deer hunting woods and meadows for obvious reasons...ie: if a P&Y buck stepped out of the edge of the woods at 120yds arcoss a small field, I wouldn't take that shot with a little 92grn x .390" ball...but would kill him where he stood if I was carrying a more robust big game caliber.
On the other hand, if someone was going to take a seat overlooking a trail crossing a drainage ditch only 25 yards away and had the discipline to pass up that P&Y buck he saw while walking in to the trail crossing, more power to him.
I've also read a number of references over the years that deer back in the day were less wary of humans and often taken at very close range, where smaller calibers would have higher odds of being effective...but in spite of finding old lead balls that might be .40cal (or .45) that does not magically mean the little 92grn x .40cal ball is a consistent 100 yard reliable performer on deer size game.
So like with many discussions, absolute across the board statements rarely work and to be honest I don't ever recall seeing a post claiming that a .40cal could not be used for deer hunting...the closest reference to something like that are some states that prohibit the .40cal.
Otherwise, the context of discussions are generally out of consideration of things like unknown distances, angles, bones, and all the vagaries of hunting conditions that play a part in delivering a ball close enough to where it needs to be to consistently do the job 100% of the time...and the fact is, the little 92grn x .40cal ball comes right out of the starting gate with more limitations that have to be considered than say a .54cal.