Simplify the following text for a Grade 12 native English-speaking person.
Original: Due to their ineffectiveness on the largest game ( up to 35 shots being recorded by some writers for a single elephant ) , they soon developed into larger caliber black powder smoothbores .
Simplified: Because they did not kill large animals very easily ( some writers said that it could take up to 35 shots to kill one elephant ) , elephant guns were soon made into larger caliber black powder smoothbores .