in Final Fantasy VII when Cloud and his friends are in the desert prison after a string of murders in Gold Saucer they initially suspect Barret have a witness says the murderer had a gun arm.
after finding Barrett in the prison he tells them about what happened at Corel about about Dyne, Marlene's biological father. in particular we see a scene in the flashback where Barret is trying to pull Dyne up after he fell off a cliff however a couple of Shinra Soliders are shown shooting along the cliff, the line of bullets appears to go though Barret's arm causing him to let go of Dyne.
Barret later says that after he got the operation to replace his useless arm with a gun he was told about another person who came in for a similar operation which lead to his suspicion (and later confirmation) that Dyne was the one committing the murders in Gold Saucer.
but from what i could tell the line of bullets only went through Barret's arm and didn't touch Dyne, so why did Dyne get the operation too?