Well I tried to hold my fingers on this one but since
others bring it up:
800 yards is nearly 1/2 mile. I'm sorry but barring
an expertly trained (which by asking these type
questions I assume not) marksman this is not a
shot to try. (notice, I did not say it was unethical).
Shoot what you want but don't rule out using your
boots and get closer. I understand there are all kinds
of "special circumstances" but for the normal person
this is too far.
Just my opinion.

God bless
PK