Board Thread:General Discussion/@comment-2600:1012:B124:477:DCD4:5F20:D416:CAFA-20180407062006/@comment-26450267-20200317023621

Its not an oversight in animation, its on purpose. His main weapon is his sword, which naturally would be in his right hand.

It makes no sense for him to train shooting with his dominant hand when he would use the gun in his left hand in an actual fight anyway.

You can see in all episodes that his gun is in the left. so when he was on the shooting range training with Sinon he was already trying to adjust having to shoot with his non dominant hand. Thats where she gives him the tips on which eye to aim with too.