Mini Rex Classes & Weights according to 2006 NMRRC Guide Book. Senior Bucks - 6 months of age and over, weight 3 to 4 1/4 pounds. Ideal weight is 4 pounds.Senior Does - 6 months of age and over, weight 3 1/4 to 4 1/2 pounds. I deal weight is 4 1/4 pounds.Junior bucks and does - Under 6 months of age, maximum weight 3 3/4 pounds. Minimum weight is 2 pounds.Note: Juniors exceeding maximum weight limits may be shown in higher age classifications. No animal may be shown in a lower age classification than its true age. Each Variety and Broken Group isto be exhibited individually.