... I don't kill black snakes because they kill the copperheads so I left him alone.
Don’t kill it, just catch it and relocate it... I just relocated a 4-5 ft one to my neighbor’s place this week ...
... he thinks they kill copperheads too and likes them for mouse control... so I give him any large black rat snake I find around the coop...
... black rat snakes are known to communally nest in winter dens with other snakes including copperheads, so the idea that they kill copperheads or at least ALL copperheads is false... but they do sometimes eat smaller snakes so I’m sure they kill a copperhead occasionally...
I could use help killing mice... but I don’t allow a large black rat snake around my coop... so I just relocate them.
To catch it grab a bucket with a lid and a rake or something and rather gently pin it’s head down and then with the other hand pick it up by the tail and lift it into the bucket... keeping the head away from your legs... and then put a lid on the bucket...
One of the best ways to rid copperheads is simply to hunt for them... go out after dark with a good flashlight and a snake killing implement of your choice on days when it’s hot and the nights are cool and look for them laying on roads, driveways, etc.
Of course keeping mice and vole numbers low keeps snakes away too...
Hope that helps if it comes back and you want to relocate it.