Out here they use mostly steel cable hidden in kind of a box like structure, oxy-acetylene torch goes through it like a hot knife thru butter.
Only thing faster would be a portable plasma cutter.
(yes they make them)
Where can I shoot ground squirrels and prairie dogs for free? Talk to me.
A .308 lock pick will not work. Obviously you have not seen
the Forest Service lock protection system I described.
Have your Will in order before you try the .308 pick.
The torch key system will work if you cut the gate down.
(There is no cable involved with the systems I have encountered.)