You might want to try the recipe posted on this page: http://www.biggamehunt.net/recipes
Its pretty good and I've tried it with elk, deer and antelope. Have not tried it with moose though. If you do try it, post back & let us know how it worked out for moose.
What does "gauge" mean anyway? As used here gauge means the number of round lead balls the same diameter as the inside of the barrel (aka the bore) that it would take to weigh one pound. It takes 12 lead balls the same diameter as a 12 gauge barrel to weigh a pound. The smaller 20 gauge would require 20 balls of that barrel diameter. The larger bore 12 gauge would require 12 lead balls of the bore diameter to weigh one pound.
In general the number of pellets in a shotgun shell...