I have 2 pretty accurate 50 yards loads with cast bullets. According to the Lyman manual they should be 900 to 1000 fps. 6 inch barrel. Is this enough for 40 to 50 yards deer hunting............
I think you are seeking an absolute rule where an absolute rule does not exist.
If someone replies, “yes, that’s a sufficient loading” and you shoot and wound a deer without a clean kill; you may place the blame on the person that approved your decision.
Your question is far too vague to be useful.
Shot placement, size of the deer, terminal performance of that bullet, intervening obstructions such as bone, are just a few variables involved.
You also don’t know if you’re really getting the velocity listed in the manual. That listed velocity may not correspond to your results.
I don’t think Whitetail Deer are bulletproof. Poachers have taken countless deer with .22 LR and .22 magnums. It’s certainly not ethical or legal but it does frequently work. Ethical hunters set the bar higher and have a responsibility to make a clean kill. Once we get above the legal threshold for caliber, the next hurdle is the hunter’s own ability. Most ethical hunters set personal limits of range and conditions for themselves. They will not take a questionable shot.
I’m not sure your question can be answered in a useful manner.