This link will take you to a description of the NMLRA Muzzleloading Rifle Silhouette targets and the ranges. I don't have the description of the targets specifically.
@fleener might have the specific dimensions.
Full list of Silhouette Matches — The NMLRA
The following is from the NMLRA Rule book:
SILHOUETTE 5700–MATCH DESCRIPTION–A match consists of 20 rounds: 4 crow targets at 50 yards 4 groundhog targets at 100 yards 4 buffalo targets at 150 yards 4 turkey targets at 175 yards 4 bear targets at 200 yards
5710–TARGETS–The silhouette targets are made from steel plate and shall be 3/8" thick for the crow and groundhog, 1/4" thick for the buffalo, turkey, and bear. The feet upon which the silhouettes rest should be made from the same type and thickness of steel as the targets. The dimensions are as follows: BASE SIZE: SILHOUETTE SIZE: Crow 2" x 4" x 3/8" Crow 12" x 8 1/2" x 3/8" Groundhog 3" x 6" x 3/8" Groundhog 6 1/2" x 13 1/2" x 3/8" Buffalo 3" x 5" x 1/4" (2 required) Buffalo 22" x 15" x 1/4" Turkey 3" x 7" x 1/4" Turkey 18" x 21" x 1/4" Bear 4" x 6" x 1/4" (2 required) Bear 13" x 35" x 1/4"
All targets are to be placed on stands off the ground. The bears and buffalo shall be placed so that the center of gravity is no more than one inch in front of the topple point. As a simple explanation, the official width of the bear’s feet is four inches. The bear should be moved carefully backward on its stand with the feet overhanging to the back side until the topple point is achieved. From that point they may be moved forward to achieve stability - but since the rules call for not more than one inch forward of this topple point. It is suggested that this final resting place be marked by spraying around the feet with target paint or otherwise, so that the bears may be placed in the same place each time they are reset. Standard NRA silhouette targets may be used at the prescribed distances.
5720–EQUIPMENT ALLOWED–Any rifle with open sights (shaders allowed) loaded with single patched round ball. Targets are designed to fall with a medium to light load for a hunting rifle. All targets can be easily toppled with a .45 caliber round ball and 60 grain charge. Any shooter who is destroying targets will be disqualified. Bullet loading blocks are allowed. Loading powder directly from flask or horn into muzzle of rifle is prohibited.
These targets will topple, if set properly, using a 45 caliber rifle and about 60 grains of black powder. I have knocked over all of the targets with my 45 caliber rifle. I have occasionally left a target on the stand with a perfect center of mass hit and I have spun a target on the stand and it still stood. Must fall to score.
Go to the NMLRA Rules Book and read all the information. The information is on page 11.
rulesbigbooks08 (msmla.org)