What are the chances to one shot a moose ?

Yesterday I just arrived at the gass station in coastal highway when I noticed a moose behind it , a bit further away in the back , I went with my business setting up a base and later on I saw that it was still there , I took out my Vaughn's rifle , aimed and shot him , and to my surprise it fell , I couldn't believe it so I went to take a closer look and it was really a moose , I got 73kg of meat , 12 guts and a pelt .

How rare is it for this to happen , most videos I watched said I needed to shoot it at least 3 times , I am playing on voyageur , does that play a role in it ?