Normal varies from person to person, but gagging is a reflex response to having something stuck in your throat. the severity of the response varies from person to person. I know some people woh do not have this relex and can swallow large sausages without a problem. then there are others, like myself, who have trouble with any large object, or even with too much food. I first discovered this about myself while playing pirate as a child, I cannot even place a knife into my mouth like they do in the movies without having to deal with my gag reflex.