This movie looks like it was shot on video for video release, but maybe there was a drive-in somewhere in 1983 that showed it on the big screen. To get us in the mood to be creeped out by snakes, there is a long scene at the beginning showing a copperhead striking at and swallowing a mouse, with another snake and mouse shown at the end. Without spoiling the ending too much, the plot is basically this: a paranoid gun maniac kills a family in Peru and steals their Inca gold piece, then buries it and hides out in a run down house in the Ozarks. After he shoots a Copperhead, lots more of them start to overrun his property. He has a run-in with the next door neighbor who is a wildlife artist, and concludes that he is collecting Copperheads to put around his house in revenge. His bible-thumping wife is constantly praying asking god to help them get rid of the snakes. He arms his family to protect the treasure and they spend all of one night shooting 41 copperheads, but the snakes keep coming. Ultimately, several people are bitten and die quickly, and one man is killed when a bag full of Copperheads is put on his head then a bucket full of even more copperheads is poured over him to finish the job.
It's obvious the screenplay writer is interested in and knowledgeable about snakes as well as guns, or at least consulted someone who is. Rare for this kind of creepy creature film, the natural history information about snakes given in the movie seems to be accurate. There is even an acceptable explanation of why so many copperheads suddenly show up at the house, so the snakes are not just runing amok and killing everybody for no reason. And there is truth in advertising about the snakes: instead of the usual harmless snakes substituted for venomous snakes that you see in most snakes attack movies, they used real live copperheads, and only copperheads. The only other kind of snake shown was a boa constrictor in South America which is appropriate. Unfortunately, they killed lots of living copperheads. During the many shots of people shooting snakes, real live snakes appear to be shot. I say "appear to be" because there's always a chance some kind of explosive was used to kill the snakes. There is definitely no Humane Society disclaimer in the end credits explaining that no animals were harmed, but there is a disclaimer that the deadliness of the copperheads was exaggerated, which you can read above.