Is is possible to be bitten by a poisonous copperhead rattlesnake and not be seriously hurt?

Yes: Most bites do not result in envenomation.

Both are pit vipers.: Approximately 25% of pit-viper bites are dry (vhttp://www.Emedicinehealth.Com/snakebite/article_em.Htm). Copperhead bites most often lead to local tissue destruction.Rattlesnake bites can cause swelling & severe pain in area of bite. The person may having bleeding, bruising, numbness, tingling, weakness, nausea, vomiting, fast heart rate, a metallic taste in mouth, bleeding disorder & confusion.

Yes: That can happen. Not all bites even get venom injected.