Tom Votava is the true "World Record Holder" for Duck Hunt without a required minimum distance. His achievement of 10,000,000 is awesome and can only be tied, not beaten. There is argument about whether or not "holding the zapper to the screen" is legitimate or not. Tom's score submission follows all of the Twin Galaxy rules for that track and is definitely a legitimate score. It's an awesome achievement.
I decided to compete at a minimum distance of 6 feet (72") which is described as the range in the manual. This is not to take away from Tom's record, but rather to foster more variation in competition on this great classic video game.