I think you will find that if locke had met him he would of remembered him... He could of not met him but had some influence in his lives though... Like the way Hurley owns lockes company... also "possibly" Jack let shannons/and dead one dad die to save his future wife... (the guy who got wheeled in had the same last name as the shannon/dead guy)
Locke has a lot of faith... something has told him to go on a journey.. his "destiny" was to go on the walkabout... what if his destiny was to get on that island, but wasn't told that part... he saw parts of his future in his dreams... Something has led him to believe that he had to get there and he did....
Des had his gun the whole time from them blowin up the hatch to seeing jack...