He's right handed but left eye dominant. There's an easy test to verify this. Look up it because the it takes longer to describe the test procedure than to actually do it. (Or if you have a monocular or even an old style camera that has a view finder, ask him to look through it. He'll naturally use his dominant eye to look through the monocular or view finder. Then you'll know for sure). I'm also right handed but left eye dominant. For long guns, I've always shot left handed (ie: used left shoulder). Yeah, you have to get guns geared towards lefties. That's why I prefer semi-autos and shotguns where the safety is ambidextrous. For example, that why I prefer the Mossberg 500 shotguns because the safety is on the tang (thumb operated). For handguns, the pistol/revolver is held right handed. But when using the sights, my head tilts to the right, so that the left (dominant eye) is actually sighting in the gun. And don't worry. I started shooting since 7 or 8 y.o., some 40+ years ago.