Marakai,
You are right in your speculation on the weight of 10 bore paradox slugs. 875 to 950 grain. However in this case I am speculating that this individual is using a 12 bore. I have a friend hunting elephant over the last couple of weeks with a 12 drilling with paradox barrels. He had settled on a load using an 875grain bullet. There are several unique features of the gun and load which may be the subject of an article in an upcoming DGJ. He had shot lion last year with the gun and conducted some terminal ballistic info at that time which has lead to this hunt.