Last year I was on the Arkansas Christmas hunt and on the next to last day, a deer gave me a broadside shot 320 yards away. I was shooting a 300winmag and I was very familiar with that rifle's ballistics at that range and it looked like an easy shot so I leaned on a power pole for support and squeezed off a shot. The deer spun around three times and died 3 feet from where he was standing. I was satisfied to see that the bullet had impacted 1" lower than the spot I was trying to hit, meat in the freezer.
The next day, I was in the same spot and saw a heard of nice deer grazing on the next ridge (ranged at 600 yards exactly) I glassed them with my scope and figured that if I had a bipod and could get prone, I could probably hit the big one. There was practically no wind and it was a level shot, ridge to ridge, on an overcast 50 degree day. Humidity was 50%. I decided not to chance it because I had not been practicing with this load at that range, but I felt confident that had I had the right rifle, and 1000 rounds through it at that range, I could have easily made that shot.
So I asked some questions on the gunsmithing side about building a lightweight custom rifle for this specific purpose. I was surprised to find quite a few members who feel that a 600 yard shot is an unethical thing to contemplate, even if Carlos Hathcock himself was behind the trigger. I always figured that 600 yards was my limit for shooting a deer no matter what rifle I was shooting or how much time I had behind it simply because it is unlikely to see a deer further than that, and it is hard to get a rifle that will still put a deer down with authority at that range. However I was not prepared to be told that I should never attempt a shot like this under any circumstances, no matter how competent I am as a rifleman.
So my question is: What is the longest shot you would consider making on a whitetail deer or similar sized critter if your back was against the wall? Hypothetically, lets say if you miss you starve and if you make the shot, it goes in the record books.
This is with your best rifle that you own, shooting jacketed or cast.