I don't know about beavers or turkeys being hard to kill, I never had that problem, but these are definitely at the top of the list.
Dad and I definitely had a problem with these guys.
Picture barrowed from NOLA.com.
We have chopped their heads off with an axe and they keep on moving and don't die for hours and hours.
Dad shot one off our front porch with his .243 and blew part of it's back shell clean off. Two days later I was walking around the perimeter of the pond and saw it just under the water and shot it point blank with my .44-40 six shooter. It was still the next day before it came floating up.
I'd call that pretty tough.
We would sit on the front porch and shoot the muskrats, turtles and snakes in the pond with our .243s.
I took this picture from the lower pond bank up to the house I grew up in. You can see the front porch. It was built in 1837 and was part of the family distillery estate.
The distillery was shut down when Prohibition started and It never recovered.
Dad was the only one that ever shot a snake from up there. A big water snake was sunning it's self on the dock at the far end of the pond and Dad manage to shoot it in the neck. Of coarse he made me drive 20 miles to see the shot he made so he could rub my nose in it.
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I was loading the Ammo he was using though!
We had a lot of fun shooting off that porch.
The beavers made a home of our lower woods. They made a down right mess out of the woods.
There was nothing but a single little crick that ran down through the woods.
The beavers made these woods into a "wetlands" and we couldn't do anything about it from that point on, to many people new about it.
As far as I know the beavers never made it to our pond.
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